Allowing Dragonmech into D&D

[Jeff the Green]

So a player has proposed a character that I'd like to allow, but I'm not sure if it'll balance with the existing party*. It'd be a kobold piloting a clockwork mech. Here are the stats to the mech as the player PMed me:

large Clockwork Mech
Size/Type: Large Construct
Hit Dice: 6d10+52 (85 hp)
Initiative: +7 (mech's Dex mod + pilot's Dex mod)
Speed: 60 ft. (12 squares) (7 mph overland)
Armor Class: 9 (-1 size), touch 9, flat-footed 9
Base Attack/Grapple: --/+10
Attack: Unarmed +9 melee (1d6+4 lethal) or Chattersword +9 melee (2d6+1d3/ x3) or Steam Gun +9 ranged (1d8)
Full Attack: Unarmed +9 melee (1d6+4 lethal) or Chattersword +9 melee (2d6+1d3/ x3) or Steam Gun +9 ranged (1d8)
Space/Reach: 10 ft./5 ft.
Special Attacks: Unarmed Attack (Ex), Trample (Ex): Tiny and smaller, 1d6 damage and if larger than Tiny Ref DC10 to trip the mech.
Special Qualities: Hardness 20: Adamantine armor plating grants great Hardness to the mech.
Saves: Fort -2, Ref +2, Will --
Abilities: Str 18, Dex 18, Con --, Int --, Wis --, Cha --
Skills: --
Feats: --
Environment: Any non-underground
Organization: Solitary with pilot
Challenge Rating: --
Treasure: None
Alignment: Usually true neutral
Advancement: None
Level Adjustment: --
Unarmed Attack (Ex): A mech does not provoke an attack of opportunity when making an unarmed attack.
Market Price: 7,665gp
Construction: Planning Time 80 days, Labor cost 0gp (pilot crafted, 19,200 man hours, 2,400 8hr days or nearly seven years), 800gp materials cost, 2,500gp adamantine armor cost, 4,000gp fixed clockwork cost, 365gp for +10 ft speed

And then there are critical hit tables and mishaps.

So I guess I'm looking at two things. First, what are general worries about allowing this thing in the game? Second, is this thing remotely balanced?

And I suppose, if it's not looking like something that's feasible, what would be a good way to make this character? I've thought of half-minotaur (modified so as to not be so freaking strong) warforged with Warforged Juggernaut (in which case the pilot would be trapped inside) and a refluffed synthesis summoner.

*For reference, Shadowcaster (with author's fixes) 9, Harmonious Knight of Freedom 6/Pious Templar 2/Crusader 1, homebrew psionic time mage 9, and Evolutionist (http://www.giantitp.com/forums/showthread.php?p=13115715) 9. The game is tier-3 and below.)

[Zanos]

It's statblock doesn't seem standard for one thing. (-2 fort and +2 dex with 6 construct HD w/ Dex 18 and Con --. Not adding dex mod to AC. ????)

It'll be tough to kill with hardness 20, but that largely depends on what you're fighting. If you're fighting a demon who's primary damage is a lot of natural attacks, it's not even going to get scratched, but if you're fighting a Giant or something it's going to take a lot of damage with AC 9.

It's damage sucks. One attack at +9 for 2d6+1d3. That's horrendous. At level 9 a melee combatant should have at least a +15-20 to hit if not a lot more.

[dysprosium]

Been awhile since I really looked at Dragonmech stuff.

IIRC it's one of those things that counts as an object and a character.

The pilot's Dexterity bonus should be taken into account for the mech's AC when actually in battle.

The adamantine hardness is the best part of the mech itself--as mentioned lots of little hits are not going to do much but big single hits will. And unless the pilot has the Repair skill, it is not going to be able to repair itself.

The BAB will be based upon the pilot's. The unarmed attack counts as a slam attack.

Nothing seems really out of whack compared to the rest of the party presented.