Thematical build questions: Master Trapsmith

[T.G. Oskar]

I'm working on a thematic build for a specialist in traps, and I have a few questions in order to see how I can maximize its main aspects. The build is currently a Kobold with levels in Rogue and Scout, then going into Trapsmith AND Combat Trapsmith, and finally adding levels in Uncanny Trickster, advancing Combat Trapsmith. It'd look like this:

Kobold Rogue 3 (Races of the Dragon racial substitition levels for 1 and 3)/Scout 4/Trapsmith 5/Combat Trapsmith 5/Uncanny Trickster 3

Stats: High Dex and Int.
Feats: Swift Ambusher (to stack Rogue and Scout levels for Skirmish and qualifying for Ambush traps), Extraordinary Trapsmith (reduces cost of main traps), Weapon Finesse or Rapid Reload (for when combat is inevitable, using finessable weapons or crossbows)
Other options: using the Races of the Dragon web enhancement for whatever is necessary (natural weapons, slight build, free weapon proficiencies and weapon familiarities.

Now, what I ask is:
How can I boost Craft (trapsmith) checks beyond the racial bonus from Kobolds, getting ranks, increasing Int, and getting Skill Focus (Craft [trapmaking])? This skill is required to determine the Search and Disable Device DCs, as well as the saving throw DCs, of booby traps, so the higher it goes, the better.
Regarding the Combat Trapsmith's combat traps: would you consider legal to apply the Ability Focus feat to one (or all) of the combat traps, to improve their DC? Combat traps have a DC based on their class level (hence, why I add the levels in Uncanny Trickster to it), so anything that boosts it beyond 17 + Int modifier makes it beneficial.

[prufock]

How can I boost Craft (trapsmith) checks beyond the racial bonus from Kobolds, getting ranks, increasing Int, and getting Skill Focus (Craft [trapmaking])? This skill is required to determine the Search and Disable Device DCs, as well as the saving throw DCs, of booby traps, so the higher it goes, the better.

Leadership - Get a marshal follower with Motivate Intelligence aura which will grant +his charisma score to your Craft checks. Give the marshal some cross-class ranks in Craft (trapsmith) so he can use the Aid action to give you an easy +2. If you have more followers, they can each make the Aid for a +2 as well, depending on what limit your DM puts on the usefulness of more helpers. If your score is high enough, have a bard follower (or cohort if necessary) to give you +2 through Inspire Competence.

Masterwork Tools - Easy +2 circumstance bonus.

Item Familiar - Risky, but you put ranks into it for extra skill bonuses. Make your Item Familiar your MW trapsmithing tool, make it out of adamantine or obdurium or something, and have some way to teleport it back to you if lost.

I should note that the DCs for combat traps are set only by 20 + class level + int, and have nothing to do with the skill check (but regular traps still do).



As for the second question, I would consider that akin to taking Ability Focus: Spells. I probably would make it affect one trap. Not sure about the RAW of this.

[Fouredged Sword]

Planer touchstone for the Craft or Artifice domain grants a flat +4 to all craft checks.

A one level dip in cleric can get you that and the craft domain for skillfocus trapsmithing, for a +7 over one level.

MIC rules allow for items that give bonuses to skill checks. Ask your DM about gloves of the master trapsmith (+X to craft trapsmithing items)

[T.G. Oskar]

Leadership - Get a marshal follower with Motivate Intelligence aura which will grant +his charisma score to your Craft checks. Give the marshal some cross-class ranks in Craft (trapsmith) so he can use the Aid action to give you an easy +2. If you have more followers, they can each make the Aid for a +2 as well, depending on what limit your DM puts on the usefulness of more helpers. If your score is high enough, have a bard follower (or cohort if necessary) to give you +2 through Inspire Competence.

Not a fan of Leadership by all means. I'm of the idea that Leadership shouldn't be a feat, but a reward similar to that on earlier D&D games

That said: why not go instead for a Marshal/Bard/Cleric/Ur-Priest/Sublime Chord and add Charisma to skill checks, Inspire Competence, Guidance of the Avatar and other skill checks? It's always gonna be 2 levels behind, but might as well exploit the heck out of it. Though, the idea is to pull it off alone, without any assistance if necessary.


Masterwork Tools - Easy +2 circumstance bonus.

Not sure if it'd fly out. Good thing I have Arms and Equipment Guide, which has a lot more masterwork itemss, not to mention Complete Adventurer. Otherwise, justifying it on a table (whether as a player or as a DM) will sound funky, no matter how legal it may seem.


Item Familiar - Risky, but you put ranks into it for extra skill bonuses. Make your Item Familiar your MW trapsmithing tool, make it out of adamantine or obdurium or something, and have some way to teleport it back to you if lost.

With all the skill ranks (between Scout and Rogue, as well as Uncanny Trickster offering 6 skill ranks/level, and with the high Int score, I can just leave the essentials and rack just about every single point left into the familiar, applying all bonuses into it. But, again, that'd be if Item Familiars are approved at the table.

I have to mention, though, that it's mostly a theoretical build which could be used on as many tables as possible, and thus easier to use options are better than ones that might not potentially fly off.


I should note that the DCs for combat traps are set only by 20 + class level + int, and have nothing to do with the skill check (but regular traps still do).

Note that I said "booby traps", not "combat traps". Booby traps are from the Trapsmith PrC in Dungeonscape, whereas Combat Traps are from the Combat Trapsmith PrC in Complete Scoundrel. The former's Search and Disable Device DCs, as well as the "attack bonuses" and Reflex save DCs from some of the traps, so in order to make them more effective, I need the ability to pull off really high rolls. For the latter, there's Uncanny Trickster to boost the class level.


As for the second question, I would consider that akin to taking Ability Focus: Spells. I probably would make it affect one trap. Not sure about the RAW of this.

Figured as much. It'd be a tad unfair to apply it to all, though completely reasonable. It'd help a lot to boost the DC of these traps, as they're basically more limited versions of spells (compare Web and Stinking Cloud to Spiderweb trap or Stinkburst trap), but pretty much infinite (once you get Improvised Materials).

The reason I ask is because Ability Focus applies only to special attacks, and the question is if Combat Traps are considered "special attacks" in order to qualify for the feat. The best part is that Combat Traps mimic some of the effects of spells, but are (Ex) abilities; if the DC is strong enough, the trapsmith can replicate the effects of disabling spells even on an AMF. The harder it is to resist, the better.


Planer touchstone for the Craft or Artifice domain grants a flat +4 to all craft checks.

Mind mentioning which Touchstone grants this? I presume it might be the Catalogues of Enlightenment, which won't come online until Plane Shift comes in.


A one level dip in cleric can get you that and the craft domain for skillfocus trapsmithing, for a +7 over one level.

I already get SF: Craft (trapmaking) from the Combat Trapsmith PrC, so it becomes kinda redundant. Plus, the class levels are already set in: the 7 levels will grant a skirmish damage bonus of 2d6, alongside 2d6 from SA; all levels from both Trapsmith and Combat Trapsmith classes, and UT to boost Combat Trapsmith.


MIC rules allow for items that give bonuses to skill checks. Ask your DM about gloves of the master trapsmith (+X to craft trapsmithing items)

Kinda iffy. It's a shame that, for all the love kobolds get in Races of the Dragon, they get no magic items that boost trapmaking at all. Thus, this might not fly with every DM (though, to be fair, I as a DM might allow it).

Funny to see how much love goes into disarming traps, but little love to boosting existing traps. It should be pretty obvious (the heroes aren't meant to build traps, but instead disarm them), but that makes the trap-making PrCs kinda weak in exchange.

[Piggy Knowles]

I don't see a problem with using Ability Focus (Combat Trapping), personally.

As far as boosting your craft check goes... as was mentioned, the Item Familiar really would help here. I know that a lot of folks consider them cheesy, but it seems like it's thematically appropriate in this case, and it should have a dramatic improvement on your craft checks.

The other option would be finding a way to pick up spells like Magecraft, Divine Insight and Guidance of the Avatar. Dipping into Unseen Seer could get you any of those added to your Trapsmith spell list, while still maintaining some of your sneak or skirmish damage. Alternatively, a few levels in Artificer would give you Magecraft, and the Spell Storing Item to pick up things like GotA.

Also, have you seen the Uncanny Trapsmith (http://community.wizards.com/go/thread/view/75882/29125157/)? It's a build by RadicalTaoist focused on using Combat Trapsmith offensively, as well as being the ultimate infiltrator. The final build stub is changeling, Rogue 3/Artificer 2/Combat Trapsmith 5/Uncanny Trickster 3/Spymaster 7. While some of it obviously goes in a different direction than your build, it has some neat tricks that allow it to use its traps offensively, such as using Fade Into Violence or Shadow Striker to set traps right under the feet of enemies without them being able to retaliate.

[prufock]

Not a fan of Leadership by all means. I'm of the idea that Leadership shouldn't be a feat, but a reward similar to that on earlier D&D games

That said: why not go instead for a Marshal/Bard/Cleric/Ur-Priest/Sublime Chord and add Charisma to skill checks, Inspire Competence, Guidance of the Avatar and other skill checks? It's always gonna be 2 levels behind, but might as well exploit the heck out of it. Though, the idea is to pull it off alone, without any assistance if necessary.

You can try to get Unseen Servant and/or Summon Monster on your spell list somehow for a +2 aid bonus, so you don't have to use Leadership and still sort of counts as "without any assistance."

Nothing stopping you from that build, I was just noting lower-level possibilities, which would save your cohort for whatever you want. There's also (I guess) action economy to consider - unless you're quickening with DMM or something, you won't be casting a spell and using Inspire Competence in the same round.


Not sure if it'd fly out. Good thing I have Arms and Equipment Guide, which has a lot more masterwork itemss, not to mention Complete Adventurer. Otherwise, justifying it on a table (whether as a player or as a DM) will sound funky, no matter how legal it may seem.
How is this even questionable? Do you have access to the PHB?

"Artisan’s Tools, Masterwork
These tools serve the same purpose as artisan’s tools (above), but masterwork artisan’s tools are the perfect tools for the job, so you get a +2 circumstance bonus on Craft checks made with them."

Trapmaking is a craft check.

[Gildedragon]

I'd swap out rogue for factotum 5ish (or 3+ at least). Get tactile trapsmith.
You get a bonus to craft checks equal to your factotum level, int to dex and str checks and skills.

[T.G. Oskar]

I don't see a problem with using Ability Focus (Combat Trapping), personally.

I don't see it either, but there's good arguments on the other side. Since it's an ability that contains lots of secondary abilities, it'd be tantamount to granting Ability Focus (spellcasting) and boost the DC of all spells by 2. Note that it can apply in different means; it could be Ability Focus (soul binding) or Ability Focus (maneuvers).

However, what I really wanted to know is if Combat Trapping counted as a "special attack" for purposes of Ability Focus, because if it weren't (if it didn't fly on some tables), then it reduces the probability of the feat applying to the character in certain tables, which requires a "plan B". It's risky whether I tried to use it as a PC ("if can use Ability Focus for his combat traps, why can't use it for my [insert ability with multiple sub-abilities]?" Same thing for using it as an NPC, because then the players would feel cheated that I can do this on my NPCs and they can't on their players. If on some tables, Ability Focus is strictly limited to "special attacks", which are defined in a way the Combat Trapping feature isn't considered as one, then I'm breaking with the rules of the group, particularly if there's no consensus on what can be defined as a special attack.

Which reminds me: by RAW, you can add a +2 on the saving throw DC required for a grappled character casting a spell under the pin of another. It's considered a "special attack (http://www.d20srd.org/srd/combat/specialAttacks.htm)", after all.

But, leaving jokes aside, at least it can be agreed that Ability Focus can apply to [I]at least one of the combat traps, because the entire ability is an [Ex] ability, so there's no way that reading can't be done (it's always an ability meant for combat, it's extraordinary, therefore it's a special attack (http://www.d20srd.org/srd/monsters/intro.htm))


As far as boosting your craft check goes... as was mentioned, the Item Familiar really would help here. I know that a lot of folks consider them cheesy, but it seems like it's thematically appropriate in this case, and it should have a dramatic improvement on your craft checks.

It's the same argument as above; if I'm introducing it on a table that doesn't generally uses it, I'm kinda disrupting the rules in that table. Basically, what's equal can't be considered a disadvantage.

Though, if it CAN be introduced on a table (or if it's already used), I presume it can combine well with a founded (read:custom-made) Item of Legacy, and that opens the door to Legacy Champion (which, depending on what moment is taken, it can boost Combat Trapsmith one or two levels higher than Uncanny Trickster).

Kinda suggests that an optimizing-inclined player should be like Batman when making builds, planning for contingencies in case key elements of their trick are turned down...


The other option would be finding a way to pick up spells like Magecraft, Divine Insight and Guidance of the Avatar. Dipping into Unseen Seer could get you any of those added to your Trapsmith spell list, while still maintaining some of your sneak or skirmish damage. Alternatively, a few levels in Artificer would give you Magecraft, and the Spell Storing Item to pick up things like GotA.

That'd imply taking levels from [I]somewhere, which most likely it'd be Scout or Rogue. Combat Trapsmith AND Trapsmith are necessary as they're the two classes mostly focused on making traps that can be applied and used in combat, and Uncanny Trickster (or Legacy Champion) is needed to boost the save DC of combat traps (and the duration of their ongoing effects). Taking them from Scout drops the Fast Movement, the Battle Fortitude, the bonus feat, and the Skirmish bonus damage (and AC), whereas dropping the Rogue means no Shrewd Trapfinding, Rapid Retreat or Evasion as a class feature, and specifically no Sneak Attack (and also the lower Trap Sense, though with the +6 bonus from both CTrapsmith and other Trapsmith, that's not really missed...)


Also, have you seen the Uncanny Trapsmith (http://community.wizards.com/go/thread/view/75882/29125157/)? It's a build by RadicalTaoist focused on using Combat Trapsmith offensively, as well as being the ultimate infiltrator. The final build stub is changeling, Rogue 3/Artificer 2/Combat Trapsmith 5/Uncanny Trickster 3/Spymaster 7. While some of it obviously goes in a different direction than your build, it has some neat tricks that allow it to use its traps offensively, such as using Fade Into Violence or Shadow Striker to set traps right under the feet of enemies without them being able to retaliate.

Hmm...good catch on feats. Like the idea; adding points in Bluff and Hide, then place a combat trap under their nose to trap them down, then remain littering the area with booby traps. With a way to make them move only in specific areas, you might as well force them to take all your booby traps and combat traps at once...


You can try to get Unseen Servant and/or Summon Monster on your spell list somehow for a +2 aid bonus, so you don't have to use Leadership and still [I]sort of counts as "without any assistance."

Nothing stopping you from that build, I was just noting lower-level possibilities, which would save your cohort for whatever you want. There's also (I guess) action economy to consider - unless you're quickening with DMM or something, you won't be casting a spell and using Inspire Competence in the same round.

Another reason why I refer to "see above". If someone bans Leadership and any other way to get cohorts in their table, that''s one leg of my build (a very good one, by the way) that gets cut. As a DM, that means I'd allow Leadership in my table, which is something I'm opposed on the grounds that it shouldn't be gotten easily (or costing one feat slot), but given out of merit (that way, you get it for "free" but you pretty much earned the right to get it). Though, on that last one (using the Master Trapsmith build as an NPC), nothing implies I can't use another NPC that buffs him. Or a minor NPC (say, a bunch of 1st-level kobold experts) providing the aid another boost (once they die from a Black Tentacles spell, that's it for them, so it's not that much of a risk.

As for Inspire Competence/casting a spell...if you're gonna optimize the heck out of the cohort, Quicken Spell via DMM isn't even the best option. There are different ways, after all. That goes without mentioning that, if it's a Bard spell, it can't be quickened unless you can reduce the time to apply metamagic on the fly to a standard action, to allow Quicken Spell to apply to it.


How is this even questionable? Do you have access to the PHB?

"Artisan’s Tools, Masterwork
These tools serve the same purpose as artisan’s tools (above), but masterwork artisan’s tools are the perfect tools for the job, so you get a +2 circumstance bonus on Craft checks made with them."

Trapmaking is a craft check.

If you wanted the extra punch, you could have said "do you have Internet (http://www.d20srd.org/srd/equipment/goodsAndServices.htm#artisansToolsMasterwork)?" I believe tone matters, even if it's not easy to capture through the screen of a computer (or smartphone, or tablet; whatever floats your boat).

It's just that mentioning "use a masterwork tool" without showing an existing example of said tool sounds wrong, in the same way you can find a "masterwork tool" for Iaijutsu Focus. There's been heated discussions for the ambiguity of this little fella over here (http://www.d20srd.org/srd/equipment/goodsAndServices.htm#toolMasterwork), which goes into "see above".


I'd swap out rogue for factotum 5ish (or 3+ at least). Get tactile trapsmith.
You get a bonus to craft checks equal to your factotum level, int to dex and str checks and skills.

I was thinking about Tactile Trapsmith, but without Factotum (and with the high need for Intelligence, it'd be just as high if not more than Dex), it's kinda pointless. Even then, it only works for Disable Device and Search, not Craft [trapmaking], so it'd be basically boosting only Disable Device and Search by adding Dex to the score (as you're returning them their bonus to Intelligence)

On the other hand, part of why I chose Rogue and Scout is because of Swift Ambusher, so that the kobold has some way to deal damage when traps aren't set (2d6 from SA, 2d6 from Skirmish via Swift Ambusher, and a +2 AC bonus on top of that). Factotum reduces that amount, only granting 1d6 if using Cunning Strike, so at least in damage I'm losing a bit (7 points on average). On the other hand, it grants proficiency in all martial weapons (so it adds a whole amount of good weapons, not to mention the use of the greatpick), Int to initiative (it's a Dex roll), treat ALL skills as class skills, and at least one 1st level spell, plus the ability to add Factotum levels to Craft [trapmaking] for a single booby trap, Disable Device or Search for more difficult traps (even if only once per day).

By now, it's best to figure whether swapping Scout for Factotum is more effective, or if the stuff from Scout is more useful: same HD, same BAB, same saves, Scout has 2 more skill points but Factotum has all class skills, Factotum has proficiency with all martial weapons and shields while Scout only offers handaxe and throwing axe. It's a hard call, though.

[Piggy Knowles]

On the other hand, part of why I chose Rogue and Scout is because of Swift Ambusher, so that the kobold has some way to deal damage when traps aren't set (2d6 from SA, 2d6 from Skirmish via Swift Ambusher, and a +2 AC bonus on top of that). Factotum reduces that amount, only granting 1d6 if using Cunning Strike, so at least in damage I'm losing a bit (7 points on average). On the other hand, it grants proficiency in all martial weapons (so it adds a whole amount of good weapons, not to mention the use of the greatpick), Int to initiative (it's a Dex roll), treat ALL skills as class skills, and at least one 1st level spell, plus the ability to add Factotum levels to Craft [trapmaking] for a single booby trap, Disable Device or Search for more difficult traps (even if only once per day).

By now, it's best to figure whether swapping Scout for Factotum is more effective, or if the stuff from Scout is more useful: same HD, same BAB, same saves, Scout has 2 more skill points but Factotum has all class skills, Factotum has proficiency with all martial weapons and shields while Scout only offers handaxe and throwing axe. It's a hard call, though.

Note that if you do replace some levels with factotum, my suggestion earlier of magecraft as a spell comes back onto the table, as it's a level 1 sor/wiz spell and therefore able to be picked up with Arcane Dilettante fairly early. +5 bonus to craft checks for the day is far from gamebreaking, but as that's going to be a solid +5 to the search and DD checks of all your traps, and the save DCs of your booby traps, that's actually quite good for you.

As to my earlier suggestion, if you were to fit in two levels of Unseen Seer for Advanced Learning, I'd consider replacing the last two levels of Trapsmith. Unseen Seer progresses casting, you nab your advanced booby traps at level 3, and booby trap DCs are based on your craft check rather than actual Trapsmith levels, so Trapsmith 3/Unseen Seer 2 means you're trading some passive boosts versus traps for +1d6 skirmish/sneak and a spell that will dramatically improve your combat trapping. That's a pretty good trade, if you ask me.

[Waker]

Dropping a level of Scout might be a good idea to allow you a one-level dip into Exemplar. You would meet all the requirements fairly easily since you will pump Craft and have Skill Focus anyways. In exchange you would get a +4 to Craft (Trapmaking) and the ability to always take a 10 on the check.

[T.G. Oskar]

Note that if you do replace some levels with factotum, my suggestion earlier of magecraft as a spell comes back onto the table, as it's a level 1 sor/wiz spell and therefore able to be picked up with Arcane Dilettante fairly early. +5 bonus to craft checks for the day is far from gamebreaking, but as that's going to be a solid +5 to the search and DD checks of all your traps, and the save DCs of your booby traps, that's actually quite good for you.

It makes creating normal traps faster, as well. The idea is to create traps in-combat, but with that immense amount of Craft (trapmaking), even making normal traps, adding the +10 to the DC to craft the trap. This can be useful for, say, protecting the party's safehouse (like any trapsmith would).


As to my earlier suggestion, if you were to fit in two levels of Unseen Seer for Advanced Learning, I'd consider replacing the last two levels of Trapsmith. Unseen Seer progresses casting, you nab your advanced booby traps at level 3, and booby trap DCs are based on your craft check rather than actual Trapsmith levels, so Trapsmith 3/Unseen Seer 2 means you're trading some passive boosts versus traps for +1d6 skirmish/sneak and a spell that will dramatically improve your combat trapping. That's a pretty good trade, if you ask me.

Avoid Disaster is pretty cool, actually. It says you can disarm a trap as an immediate action 1/day to avoid springing the trap.

That said, the gains seem to be balanced against the losses. Adding 1 point of Sneak Attack (or Skirmish, depending on whether Scout is kept or not), an extra spell (gained exactly when you gain your first 3rd level spell) and Silent Spell for free clearly outweighs the loss of SR against traps, a loss of +1 to trap sense and Dance through Danger, though the loss of +2 bonus to Disable Device, Open Lock and Search checks and Avoid Disaster hurts a bit. It's a considerable choice.


Dropping a level of Scout might be a good idea to allow you a one-level dip into Exemplar. You would meet all the requirements fairly easily since you will pump Craft and have Skill Focus anyways. In exchange you would get a +4 to Craft (Trapmaking) and the ability to always take a 10 on the check.

...Hmm, good catch, though the main reason why you choose Exemplar won't be acquired (which is most definitely not the bonus to the check and Skill Mastery with said skill). It'd be interesting to find ways to create Tippy traps and boost Craft (trapmaking) to the extent you create fanatics out of them. Heck...it actually makes sense!

Suddenly, Rogue 3/Factotum 3/Combat Trapsmith 5/Trapsmith 2/Unseen Seer 2/Uncanny Trapsmith 3 doesn't look so bad...

[Waker]

Well I wouldn't use the Exemplar to make an odd Diplomancer, but one could do that.
"Behold, a pit trap!"
"Magnificent..."

[prufock]

If someone bans Leadership and any other way to get cohorts in their table, that''s one leg of my build (a very good one, by the way) that gets cut.
Couldn't you just ask the DM prior to the game whether it's banned? Of course, if you don't want to use it for personal taste it's moot.


If you wanted the extra punch, you could have said "do you have Internet (http://www.d20srd.org/srd/equipment/goodsAndServices.htm#artisansToolsMasterwork)?" I believe tone matters, even if it's not easy to capture through the screen of a computer (or smartphone, or tablet; whatever floats your boat).
It exists in both the PHB and the SRD. I'm not sure how that changes what I said.

There is an existing example, I quoted the text. MW artisan's tools grant a bonus specifically to craft checks.

[Piggy Knowles]

Suddenly, Rogue 3/Factotum 3/Combat Trapsmith 5/Trapsmith 2/Unseen Seer 2/Uncanny Trapsmith 3 doesn't look so bad...

You're missing two levels... I assume you didn't intend to drop Trapsmith to 2, since that loses advanced booby traps, and to add a level of Exemplar? So that would be Rogue 3/Factotum 3/Combat Trapsmith 5/Trapsmith 3/Unseen Seer 2/Uncanny Trickster 3/Exemplar 1.

[Fouredged Sword]

Buy lots of crossbows. You can lay them 3 to a square and get something line +40 or so to the attack roll, so they are likely to hit.

Then fill an area with them, and lure an enemy into it.

[T.G. Oskar]

Couldn't you just ask the DM prior to the game whether it's banned? Of course, if you don't want to use it for personal taste it's moot.

It's less personal taste and more a difference in opinion, just in case.

Thing is, if a DM allows it, then you could be an almost complete antisocial and people will still choose to follow you as long as you choose the feat, while feat-starved people with incredible leadership skills can't do so because it requires you to spend a feat slot. It kinda stresses credibility.

Still: nothing beats having a plan B for when plan A is a no-go, right?


It exists in both the PHB and the SRD. I'm not sure how that changes what I said.

There is an existing example, I quoted the text. MW artisan's tools grant a bonus specifically to craft checks.

It's not the what, but the how. Note that I placed more emphasis on the tone: hearing "do you have a PHB?" seemed a bit demeaning. That sounded like it was on the same level of obvious as the Core Mechanic (something that, by no means whatsoever, should be forgotten), rather than as obvious as buying a weapon; it's still obvious, but the priority changes based on the build. Frankly, it sounds like you were chastising me rather than reminding me; hence, the remark. When I said the thing about the SRD, it's because it would have sounded harsher, but that doesn't mean the remark about the PHB didn't sound harsh enough: one sounds like you didn't do your job, the other hammered the idea that there's no excuse not to have known about it.

--

Now, I have a good mock-up of the build, level-by-level. Running through it and watching all the options, Exemplar has only a flimsy excuse to stay in. Also chose to go with Unseen Seer, but getting in was a head-ache feat-wise (if it weren't for Exemplar and Factotum levels, I wouldn't have gotten in because of Spellcraft and Sense Motive)

Factotum adds martial weapon and shield proficiency (if using the Races of the Dragon WE, that means the kobold gains proficiency with the greatpick), Inspiration points, the ability to add Int to attack rolls, damage rolls, saving throws, skill checks, or AC; Int modifier to Str and Dex checks (and the skill checks they respectively modify), and a 1st level Wizard spell, plus all skills as class skills (useful for adding Sense Motive and Spellcraft, and advance Use Magic Device). Shifting it with 3 levels of Spellthief can be pretty potent, considering Master Spellthief.

Exemplar, on the other hand...Skill Mastery is great, but the Skill Artistry bonus is a competence bonus, so Guidance of the Avatar will overcome it.

Feat-wise, I chose for Weapon Finesse, Fade to Violence, Craven, Practiced Spellcaster, Shadow Striker and Ability Focus (combat trapping), alongside Skill Focus (Craft [trapmaking]) and Extraordinary Trapsmith. Silent Spell is a bonus feat from Unseen Seer. If I were to get other feats, and the DCS was accessible, then Fade to Violence (after getting Shadow Striker) and Silent Spell can be shuffled to two new spells. That's without using flaws, in case they're not allowed, so that's up to 4 feat slots to play with in case everything is allowed.

The resumed mock-up would be as follows:
Race: Kobold
Level Progression: Rogue 3 (Kobold Substitution Level 1 & 3)/Factotum 3/Trapsmith 3/Combat Trapsmith 1/Exemplar 1/Unseen Seer 2/Combat Trapsmith 4+/Uncanny Trickster 3

Starting Stats:
Str 10, Dex 14, Con 13, Int 15, Wis 8, Cha 12 (elite array)
Str 12, Dex 14, Con 14, Int 15, Wis 8, Cha 12 (28-pt. buy)
Str 10, Dex 14, Con 16, Int 16, Wis 8, Cha 12 (32-pt. buy)

Racial Stat Adjustment:
Str 6, Dex 16, Con 11, Int 15, Wis 8, Cha 12 (elite array)
Str 8, Dex 16, Con 12, Int 15, Wis 8, Cha 12 (28-pt. buy)
Str 6, Dex 16, Con 14, Int 16, Wis 8, Cha 12 (32-pt. buy)

Feats: Skill Focus (Craft [trapmaking]), Weapon Finesse, Fade to Violence, Craven, Practiced Spellcaster (Trapsmith), Shadow Striker, Extraordinary Trapsmith, Ability Focus (Combat Trapping)

Skill Points (at 20th level): Bluff 12 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (poisonmaking) 5 ranks, Craft (trapmaking) 23 ranks, Diplomacy 6 ranks, Disable Device 23 ranks, Hide 20 ranks, Open Lock 23 ranks, Move Silently 20 ranks, Search 23 ranks, Sense Motive 12 ranks, Sleight of Hand 12 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 16 ranks

Skill Tricks: Clarity of VisionB, Clever Improviser, Conceal Spellcasting, Group Fake-OutB, Mosquito's BiteB, Opening Tap, Spot the Weak Point, Timely Misdirection

Any other ideas you might want to add? Was thinking on replacing Uncanny Trickster with a major bloodline...

[Kuulvheysoon]

Very well thought out (as most of your posts are).

The only thing that I can suggest to change is from a normal kobold to a desert kobold (UA). Trade out that penalty to Constitution for a penalty to Wisdom, lose the light sensitivity and get Heat Endurance as a bonus feat.

[Piggy Knowles]

I kind of love it. Nicely done.

You can probably afford to shift a few skill points out of DD/Open Lock. It wouldn't be a bad idea to get that craft (alchemy) score higher, since one of the most fun things to do with the trapsmith's booby traps is to use the drop traps alongside alchemical items. GotA + fabricate can cover most items in the higher levels, but it's still a concern.

[T.G. Oskar]

Very well thought out (as most of your posts are).

The only thing that I can suggest to change is from a normal kobold to a desert kobold (UA). Trade out that penalty to Constitution for a penalty to Wisdom, lose the light sensitivity and get Heat Endurance as a bonus feat.

Somewhat interesting, but there's the Will penalty (which would intensify a bit more). Heat endurance is a racial feature, not an actual feat: it'd be interesting to have Kobold Endurance replacing it (it allows you to replace the Endurance feat if you gain it as a bonus feat; if the Heat Endurance feat counted as Endurance for all things, you could justify replacing Heat Endurance for Kobold Endurance.


I kind of love it. Nicely done.

You can probably afford to shift a few skill points out of DD/Open Lock. It wouldn't be a bad idea to get that craft (alchemy) score higher, since one of the most fun things to do with the trapsmith's booby traps is to use the drop traps alongside alchemical items. GotA + fabricate can cover most items in the higher levels, but it's still a concern.

I'd need to gauge how many points can I drop and still be effective at DD/Open Lock (and maybe Search as well). I could raise Craft (alchemy) and Craft (poisonmaking) to craft as many alchemical items and poisons as possible, because I also intend on exploiting arrow traps for all they're worth, but I can't let Disable Device, Open Lock and Search too low.

--

So, I think I've tweaked the build as much as I could, so here's the level-by-level schematic of how the build would progress. I've done this recently (mostly for a d20 Modern character I'm playing, because I needed to spend the skill points wisely enough to get to a PrC quickly enough and still get the right feel for the character), and it helps a lot, because each level is a snapshot of the character without weapons and whatnot, and thus can be used to determine its general power at specific levels. It's also a big help to determine when and where I should spend my skill points, and it has a lot more information than just posting the finished build.

Level 1: Rogue 1 (Kobold racial substitution level)
Hit Dice: d4
Base Attack Bonus: +0 Fortitude: +0 Reflex: +2 Will: +0
Skill Points: 40 – Bluff 4 ranks, Craft (trapmaking) 4 ranks, Diplomacy 4 ranks, Disable Device 4 ranks, Hide 4 ranks, Open Lock 4 ranks, Move Silently 4 ranks, Search 4 ranks, Spot 4 ranks, Use Magic Device 4 ranks
Class Features: Rapid Retreat (5-ft. bonus to speed when withdrawing), Shrewd Trapfinding +2 (bonus on Disable Device checks to disable traps, Search checks to find traps), Sneak Attack +1d6

Level 2: Rogue 2
Hit Dice: d6
Base Attack Bonus: +1 Fortitude: +0 Reflex: +3 Will: +0
Skill Points: 8 – Bluff 4 ranks, Craft (trapmaking) 5 ranks, Diplomacy 5 ranks, Disable Device 5 ranks, Hide 5 ranks, Open Lock 5 ranks, Move Silently 5 ranks, Search 5 ranks, Spot 5 ranks, Use Magic Device 5 ranks
Skill Trick: Clever Improviser (ignore penalty for Disable Device and Open Lock checks made without tools)
Class Features: Evasion (take no damage on successful Reflex save on attacks with Reflex [half] or Reflex [partial])

Level 3: Rogue 3 (Kobold racial substitution level)
Hit Dice: d4
Base Attack Bonus: +2 Fortitude: +1 Reflex: +3 Will: +1
Skill Points: 10 – Bluff 6 ranks, Craft (trapmaking) 6 ranks, Diplomacy 6 ranks, Disable Device 6 ranks, Hide 6 ranks, Open Lock 6 ranks, Move Silently 6 ranks, Search 6 ranks, Spot 6 ranks, Use Magic Device 6 ranks
Feat: Weapon Finesse (use Dex modifier instead of Str modifier on attack rolls with light weapons, rapier, spiked chain, whip)
Class Features: Improved Trap Sense +2, Shrewd Trapfinding +4, Sneak Attack +2d6

Level 4: Rogue 3/Factotum 1
Hit Dice: d8
Base Attack Bonus: +2 Fortitude: +1 Reflex: +5 Will: +1
Skill Points: 9 –Bluff 6 ranks, Craft (trapmaking) 7 ranks, Diplomacy 6 ranks, Disable Device 7 ranks, Hide 7 ranks, Open Lock 7 ranks, Move Silently 7 ranks, Search 7 ranks, Sense Motive 1 rank, Spellcraft 1 rank, Spot 6 ranks, Use Magic Device 7 ranks
Ability Score Increase: Int +1
Class Features: Cunning Insight (spend 1 inspiration point to add Int modifier as competence bonus to attack roll, damage roll or saving throw), Cunning Knowledge (spend 1 inspiration point to add factotum level to a single skill check with a skill that has at least 1 rank; 1/day/skill)
Inspiration Points: 2

Level 5: Rogue 3/Factotum 2
Hit Dice: d8
Base Attack Bonus: +3 Fortitude: +1 Reflex: +6 Will: +1
Skill Points: 9 – Bluff 6 ranks, Craft (trapmaking) 8 ranks, Diplomacy 6 ranks, Disable Device 8 ranks, Hide 8 ranks, Open Lock 8 ranks, Move Silently 8 ranks, Search 8 ranks, Sense Motive 2 ranks, Spellcraft 2 ranks, Spot 6 ranks, Use Magic Device 8 ranks
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 0 level)
Inspiration Points: 3

Level 6: Rogue 3/Factotum 3
Hit Dice: d8
Base Attack Bonus: +4 Fortitude: +2 Reflex: +6 Will: +2
Skill Points: 9 – Bluff 6 ranks, Craft (trapmaking) 9 ranks, Diplomacy 6 ranks, Disable Device 9 ranks, Hide 9 ranks, Open Lock 9 ranks, Move Silently 9 ranks, Search 9 ranks Sense Motive 3 ranks, Spellcraft 3 ranks, Spot 6 ranks, Use Magic Device 9 ranks
Feat: Fade to Violence (if wearing light or no armor and carry nothing, convince one foe of being inoffensive)
Class Features: Brains over Brawn (add Int modifier to Strength checks, Dexterity checks, Strength- and Dexterity-based skill checks), Cunning Defense (spend 1 inspiration point as swift action to add Int modifier as dodge bonus to AC against 1 opponent for 1 round)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Inspiration Points: 3

Level 7: Rogue 3/Factotum 3/Trapsmith 1
Hit Dice: d6
Base Attack Bonus: +4 Fortitude: +2 Reflex: +8 Will: +2
Skill Points: 9 – Bluff 6 ranks, Craft (alchemy) 1 rank, Craft (trapmaking) 10 ranks, Diplomacy 6 ranks, Disable Device 10 ranks, Hide 9 ranks, Open Lock 10 ranks, Move Silently 9 ranks, Search 10 ranks, Sense Motive 6 ranks, Sleight of Hand 2 ranks, Spellcraft 3 ranks, Spot 8 ranks, Use Magic Device 9 ranks
Class Feature: Booby traps (allows making simple mechanical traps and place them as full-round action), Master Disarmer (add class level to Disable Device, Open Lock, Search checks), Trap Sense +3
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1 (1+1 bonus) –fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), haste (http://www.d20srd.org/srd/spells/haste.htm)
Inspiration Points: 3

Level 8: Rogue 3/Factotum 3/Trapsmith 2
Hit Dice: d6
Base Attack Bonus: +5 Fortitude: +2 Reflex: +9 Will: +2
Skill Points: 9 – Bluff 6 ranks, Craft (alchemy) 2 ranks, Craft (trapmaking) 11 ranks, Diplomacy 6 ranks, Disable Device 11 ranks, Hide 9 ranks, Open Lock 11 ranks, Move Silently 9 ranks, Search 11 ranks, Sense Motive 6 ranks, Sleight of Hand 4 ranks, Spellcraft 3 ranks, Spot 10 ranks, Use Magic Device 9 ranks
Ability Score Increase: Con +1
Class Feature: Arrow Proof (DR 5/- against the effects of traps), Quick Fingers (reduce time required to make Disable Device checks)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (2+1 bonus) –fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm)
Inspiration Points: 3

Level 9: Rogue 3/Factotum 3/Trapsmith 3
Hit Dice: d6
Base Attack Bonus: +6 Fortitude: +3 Reflex: +9 Will: +3
Skill Points: 7 – Bluff 6 ranks, Craft (alchemy) 3 ranks, Craft (trapmaking) 12 ranks, Diplomacy 6 ranks, Disable Device 12 ranks, Hide 9 ranks, Open Lock 12 ranks, Move Silently 9 ranks, Search 12 ranks, Sense Motive 6 ranks, Sleight of Hand 4 ranks, Spellcraft 3 ranks, Spot 12 ranks, Use Magic Device 9 ranks
Skill Trick: Spot the Weak Point (next attack considered touch attack)
Feat: Craven (-2 penalty on saving throws against fear, deal 1 point of damage per character level on successful sneak attack)
Class Features: Booby Traps (allows creation of advanced mechanical traps), Trap Sense +4, Unweave 3/day (as dispel magic (http://www.d20srd.org/srd/spells/dispelMagic.htm) but works only with traps; CL 5 + class level)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (2+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (1+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm)
Inspiration Points: 3

Level 10: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 1
Hit Dice: d6
Base Attack Bonus: +6 Fortitude: +5 Reflex: +11 Will: +3
Skill Points: 7 – Bluff 6 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 13 ranks, Diplomacy 6 ranks, Disable Device 13 ranks, Hide 9 ranks, Open Lock 13 ranks, Move Silently 9 ranks, Search 13 ranks, Sense Motive 6 ranks, Sleight of Hand 6 ranks, Spellcraft 3 ranks, Spot 12 ranks, Use Magic Device 9 ranks
Skill Trick: Conceal Spellcasting (conceal spellcasting from onlookers)
Class Feature: Trap Sense +5
Combat Traps: Enfeebler (fatigues target), Glitterburst (makes invisible target visible)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (2+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (1+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm)
Inspiration Points: 3

Level 11: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 1/Exemplar 1
Hit Dice: d6
Base Attack Bonus: +6 Fortitude: +5 Reflex: +11 Will: +5
Skill Points: 11 – Bluff 8 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 14 ranks, Diplomacy 6 ranks, Disable Device 14 ranks, Hide 9 ranks, Open Lock 14 ranks, Move Silently 9 ranks, Search 14 ranks, Sense Motive 8 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks (missing 1 rank...)
Class Feature: Skill Artistry (gain +4 competence bonus on all Craft [trapmaking] checks), Skill Mastery (take 10 on Craft [trapmaking], Disable Device, Open Lock and Spot checks even if stress and distractions would prevent it)
Combat Traps: Enfeebler (fatigues target), Glitterburst (makes invisible target visible)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (2+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (1+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm)
Inspiration Points: 3

Level 12: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 1/Exemplar 1/Unseen Seer 1
Hit Dice: d4
Base Attack Bonus: +6 Fortitude: +5 Reflex: +11 Will: +7
Skill Points: 9 – Bluff 9 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 15 ranks, Diplomacy 6 ranks, Disable Device 14 ranks, Hide 12 ranks, Open Lock 14 ranks, Move Silently 12 ranks, Search 15 ranks, Sense Motive 8 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Ability Score: Con +1
Feat: Practiced Spellcaster (increase caster level for Trapsmith spells by 4)
Class Feature: Sneak Attack +3d6
Combat Traps: Enfeebler (fatigues target), Glitterburst (makes invisible target visible)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm)
Inspiration Points: 3

Level 13: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 1/Exemplar 1/Unseen Seer 2
Hit Dice: d4
Base Attack Bonus: +7 Fortitude: +5 Reflex: +11 Will: +8
Skill Points: 7 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 16 ranks, Diplomacy 6 ranks, Disable Device 14 ranks, Hide 12 ranks, Open Lock 14 ranks, Move Silently 12 ranks, Search 16 ranks, Sense Motive 12 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Skill Trick: Opening Tap (open a lock as a swift action)
Bonus Feat: Silent Spell (ignore verbal component of spells; use spell slot 1 level higher)
Combat Traps: Enfeebler (fatigues target), Glitterburst (makes invisible target visible)
Class Feature: Advanced Learning (add divination spell of up to 3rd level to list of spells known)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 14: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 2/Exemplar 1/Unseen Seer 2
Hit Dice: d6
Base Attack Bonus: +8 Fortitude: +6 Reflex: +12 Will: +8
Skill Points: 9 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 17 ranks, Diplomacy 6 ranks, Disable Device 16 ranks, Hide 14 ranks, Open Lock 16 ranks, Move Silently 13 ranks, Search 17 ranks, Sense Motive 12 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Bonus Feat: Shadow Striker (enables use of three tactical feats to evade notice, fade away from area, or execute a ghost strike)
Combat Traps: Enfeebler (fatigues target), Entangler (entangles target), Glitterburst (makes invisible target visible)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 15: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 3/Exemplar 1/Unseen Seer 2
Hit Dice: d6
Base Attack Bonus: +9 Fortitude: +6 Reflex: +12 Will: +9
Skill Points: 9 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 18 ranks, Diplomacy 6 ranks, Disable Device 18 ranks, Hide 15 ranks, Open Lock 18 ranks, Move Silently 15 ranks, Search 18 ranks, Sense Motive 12 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Feat: Extraordinary Trapsmith (reduces cost of raw materials to make trap by 25%; if a kobold, reduce by 50% instead)
Class Feature: Trap sense +6
Combat Traps: Enfeebler (fatigues target), Entangler->Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 16: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 4/Exemplar 1/Unseen Seer 2
Hit Dice: d6
Base Attack Bonus: +10 Fortitude: +7 Reflex: +13 Will: +10
Skill Points: 7 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (trapmaking) 19 ranks, Diplomacy 6 ranks, Disable Device 19 ranks, Hide 17 ranks, Open Lock 19 ranks, Move Silently 16 ranks, Search 19 ranks, Sense Motive 12 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Skill Trick: Timely Misdirection (make Bluff check to ignore attack of opportunity)
Ability Score Increase: Con +1
Class Features: Improvised materials (craft combat traps without required kit by increasing Craft [trapmaking] check by 5)
Combat Traps: Enfeebler (fatigues target), Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible), Sleeper (target falls asleep)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 17: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 5/Exemplar 1/Unseen Seer 2
Hit Dice: d6
Base Attack Bonus: +10 Fortitude: +7 Reflex: +13 Will: +10
Skill Points: 9 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (poisonmaking) 2 ranks, Craft (trapmaking) 20 ranks, Diplomacy 6 ranks, Disable Device 20 ranks, Hide 18 ranks, Open Lock 20 ranks, Move Silently 18 ranks, Search 20 ranks, Sense Motive 12 ranks, Sleight of Hand 6 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 10 ranks
Class Feature: Expert Trapsetter (set combat traps as standard actions without provoking attacks of opportunity), Trap Sense +7
Combat Traps: Enfeebler (fatigues target), Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible), Sleeper (target falls asleep), Spiderweb (web fills small area), Stinkburst (stinking cloud fills target square)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 18: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 5/Exemplar 1/Unseen Seer 2/Uncanny Trickster 1
Hit Dice: d6
Base Attack Bonus: +10 Fortitude: +7 Reflex: +15 Will: +10
Skill Points: 11 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (poisonmaking) 3 ranks, Craft (trapmaking) 21 ranks, Diplomacy 6 ranks, Disable Device 21 ranks, Hide 19 ranks, Open Lock 21 ranks, Move Silently 19 ranks, Search 21 ranks, Sense Motive 12 ranks, Sleight of Hand 8 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 12 ranks
Skill Trick: Clarity of Vision (notice invisible enemies for 1 round)
Feat: Ability Focus (increase DC of combat trapping special attack by 2)
Class Feature: Favorite Trick (able to use Spot the Weak Point skill trick twice per day)
Combat Traps: Enfeebler (fatigues target), Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible), Sleeper (target falls asleep), Spiderweb (web fills small area), Stinkburst (stinking cloud fills target square)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 19: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 5/Exemplar 1/Unseen Seer 2/Uncanny Trickster 2
Hit Dice: d6
Base Attack Bonus: +11 Fortitude: +7 Reflex: +16 Will: +10
Skill Points: 11 – Bluff 10 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (poisonmaking) 4 ranks, Craft (trapmaking) 22 ranks, Diplomacy 6 ranks, Disable Device 22 ranks, Hide 20 ranks, Open Lock 22 ranks, Move Silently 20 ranks, Search 22 ranks, Sense Motive 12 ranks, Sleight of Hand 10 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 14 ranks
Skill Trick: Group Fake-Out (feint against multiple foes simultaneously)
Class Feature: Favorite Trick (able to use Spot the Weak Point, Timely Misdirection skill tricks twice per day)
Combat Traps: Enfeebler (fatigues target), Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible), Sleeper (target falls asleep), Stinkburst (stinking cloud fills target square)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

Level 20: Rogue 3/Factotum 3/Trapsmith 3/Combat Trapsmith 5/Exemplar 1/Unseen Seer 2/Uncanny Trickster 2
Hit Dice: d6
Base Attack Bonus: +12 Fortitude: +8 Reflex: +16 Will: +11
Skill Points: 11 – Bluff 12 ranks, Concentration 1 rank, Craft (alchemy) 4 ranks, Craft (poisonmaking) 5 ranks, Craft (trapmaking) 23 ranks, Diplomacy 6 ranks, Disable Device 23 ranks, Hide 20 ranks, Open Lock 23 ranks, Move Silently 20 ranks, Search 23 ranks, Sense Motive 12 ranks, Sleight of Hand 12 ranks, Spellcraft 4 ranks, Spot 12 ranks, Use Magic Device 16 ranks
Skill Trick: Mosquito’s Bite (Flat-footed target does not notice damage dealt with light weapon)
Ability Score Increase: Wis +1
Class Feature: Favorite Trick (able to use Clarity of Vision, Spot the Weak Point, Timely Misdirection skill tricks twice per day), Tricky Defense (in any round performing a skill trick, gain a +1 competence bonus to saving throws until next turn)
Combat Traps: Enfeebler (fatigues target), Flashbang (blinds and deafens target), Glitterburst (makes invisible target visible), Sleeper (target falls asleep), Spiderweb (web fills small area), Stinkburst (stinking cloud fills target square)
Arcane Dilettante (DC = 10 + spell level + Int mod): 1 spell (up to 1st level)
Spellcasting (DC = 10 + spell level + Int mod): 1st (3+1 bonus)—fox’s cunning (http://www.d20srd.org/srd/spells/foxsCunning.htm), gaseous form (http://www.d20srd.org/srd/spells/gaseousForm.htm), haste (http://www.d20srd.org/srd/spells/haste.htm), knock (http://www.d20srd.org/srd/spells/knock.htm); 2nd (2+1 bonus)—dimension door (http://www.d20srd.org/srd/spells/dimensionDoor.htm), {divine insight or guidance of the avatar), lesser globe of invulnerability (http://www.d20srd.org/srd/spells/globeOfInvulnerabilityLesser.htm), stoneskin (http://www.d20srd.org/srd/spells/stoneskin.htm); 3rd (1+1 bonus)—break enchantment (http://www.d20srd.org/srd/spells/breakEnchantment.htm), fabricate (http://www.d20srd.org/srd/spells/fabricate.htm)
Inspiration Points: 3

I'll ask you questions about another build that I'm working on, and where I need more help, but that'll be part of another thread. I believe this one is already threatening the Uncanny Trapsmith on its own turf, sacrificing a bit of diversity for sheer purity of purpose...

[Diovid]

I once created something like this, though it was even more specialized. Too bad I never actually got to play it:

Race: Earth Kobold (http://www.d20srd.org/srd/variant/races/elementalRacialVariants.htm#earthKobolds) (using the Kobold update (http://www.wizards.com/default.asp?x=dnd/we/20060420a))
Build: Rogue 3 / Kobold Paragon (http://www.wizards.com/default.asp?x=dnd/we/20060127a) 2 / Trapsmith 5 / Combat Trapsmith 5* / Exemplar 1 / Marshal 1 / Uncanny Trickster 3 (advancing Combat Trapsmith)
Rogue variants: 1st kobold substitution level (http://www.wizards.com/default.asp?x=dnd/ex/20060106a&page=3), quick fingers (Dungeonscape), martial rogue (http://www.d20srd.org/srd/variant/classes/variantCharacterClasses.htm#rogue)
Trait: Specialized (http://www.d20srd.org/srd/variant/buildingCharacters/characterTraits.htm#specialized) (craft (trapmaking))
* Also note it's adaptation section.

Possible feats:

Apprentice (Craftsman) - DMG II
Favored in Guild* - DMG II
Extraordinary Trapsmith - Races of the Dragon
Combat Tinkering - Dungeonscape
Trap Sensitivity - Dungeonscape
Trap Engineer - Dungeonscape
Trapmaster - Lost Empires of Faerun
Craft Expertise - Dragon Magazine #339
Guerilla Trapsmith - Dragon Magazine #342
Trap Mastery - Dragon Mastery #347

* If the DM allows a crafting or trapping guild to be selected.