Magic Item and Casting question

[Thatwarforged]

So if I have a magic item that has (Insert Misc. Spell here) at-will or however many times a day. When that spell gets used do I (or whomever is activating it) count as the caster of said spell or does the magic item count as said caster?

Now here is why (You don't have to read it if you don't want to)

I was building a sphere of power character (as a test) and as the character evolved during creation it started looking a bit like a druid without shapechanging, but had warp magic including the create demiplane advanced talent. So I thought what if I created a nature preserve demiplane meaning that I need a lot of space and a 2 miles diameter takes some 100 years with a normal character casting it with all its spell points. So I want to use the magic item that cast it then give it a bestow intelligence item so it can continue to cast it every round 24/7. As I thought of this, I got into an argument with myself over what it should be so I need to know what the ruling is about this. So that I know if my character regardless if the item is intelligent or not is going to have to sit there and activate it manually.

[With a box]

So if I have a magic item that has (Insert Misc. Spell here) at-will or however many times a day. When that spell gets used do I (or whomever is activating it) count as the caster of said spell or does the magic item count as said caster?

Now here is why (You don't have to read it if you don't want to)

I was building a sphere of power character (as a test) and as the character evolved during creation it started looking a bit like a druid without shapechanging, but had warp magic including the create demiplane advanced talent. So I thought what if I created a nature preserve demiplane meaning that I need a lot of space and a takes some 100 years with a normal character casting it with all its spell points. So I want to use the magic item that cast it then give it a bestow intelligence item so it can continue to cast it every round 24/7. As I thought of this, I got into an argument with myself over what it should be so I need to know what the ruling is about this. So that I know if my character regardless if the item is intelligent or not is going to have to sit there and activate it manually.
pathfinder create demiplane has 1hour/level duration, and (I assume you are 20th level and can cast 9th, the greater one) up to 20 10-ft. cubes/level and 6 hour casting time
20*20*10*10 ft^2 of demiplane when every casting, 2 miles diameter means 8.758*10^7 sq feet, so you need to cast it 2190 times and you need to spend 550 day to casting time alone
but you need to cast it in every 20 days...
you can make this permanent with the permanency spell, but it cost 2190*22,500= 49,275,000gp

but your plane is still has 10ft ceiling. if you wand to expend it to 30ft, triple everything.

[Thatwarforged]

Spheres of Power which is a alternative casting system has a talent called Create Demiplane which makes a permanent demiplane but it only creates CL in 10 ft squares so considerably less then the spell. It really doesn't answer the question though and I'm was going for caster level 10 (Since most games don't begin at 20th level).

[Crake]

If you're allowed, use genesis from 3.5. Costs 25k per casting (pf replacing the 5000xp with *5gp) and each casting increases the radius by 180ft. You would need 59 castings to increase the size to 2 miles, for a total of 1,475,000gp, and at 1 week per casting, 58 weeks (almost a full year of casting). But it is instantaneous, and a spherical radius, which you could fill halfway with dirt and have a decent skydome.

On top of that you can add planar traits as you desire to it.

[Der_DWSage]

To answer the relevant question-the item uses its own caster level. A rod of Create Demiplane (using Spheres of Power item creation rules, it's the only item that can cast at will) is going to run you 5000 GP per caster level. (1000 GP for creation, 1 complexity base, adding Bend Space is another +1, 3 spell points is another +3. And this is if the GM doesn't rule that it also needs the other pre-requisite talents, which would be another 3 complexity.) Additionally, it has to be minimum caster level 15, so this rod is running 75,000 GP minimum. That's if you're crafting it yourself, and you're not purchasing it, and the GM is mildly lenient.

[Thatwarforged]

Okay I am not asking about caster level but whom is the caster. Me for using the item to cast the spell or the item because it is storing and is why im casting the spell? This matters when it comes to Create demiplane for the options I can utilize if I have nature sphere or weather sphere but also because if I'm the caster that means if I make the item intelligent and its in a preexisting demiplane I used it to create then I cant have it cast 24/7 but if its the caster level I can have it cast 24/7 but cant use my own spheres for extra effects. Do you catch my drift?

[nyjastul69]

Okay I am not asking about caster level but whom is the caster. Me for using the item to cast the spell or the item because it is storing and is why im casting the spell? This matters when it comes to Create demiplane for the options I can utilize if I have nature sphere or weather sphere but also because if I'm the caster that means if I make the item intelligent and its in a preexisting demiplane I used it to create then I cant have it cast 24/7 but if its the caster level I can have it cast 24/7 but cant use my own spheres for extra effects. Do you catch my drift?

Is the item in question a spell completion (http://www.d20srd.org/srd/magicItems/magicItemBasics.htm#spellCompletion) item, a spell trigger (http://www.d20srd.org/srd/magicItems/magicItemBasics.htm#spellTrigger) item, a command word (http://www.d20srd.org/srd/magicItems/magicItemBasics.htm#commandWord) item, or a use activated (http://www.d20srd.org/srd/magicItems/magicItemBasics.htm#useActivated) item?

Edit: Sorry, I missed the the PF label. :/

[Thatwarforged]

Its fine pretty much similar enough rules to utilize your answer if not someone can help me. The item is use-activated (I believe its wording and ect. make it seem that way anyway.).

[Der_DWSage]

Right, lemme make it more clear. The item is the caster, for all intents and purposes.