An animated object gets a restricted amount of CP to choose from. Hardness 20 costs 6 CP, which is only granted to a Gargantuan or larger object.
If I animate an adamantine key or mop or some such, I can just break it over my knee at that point, right? As nothing smaller than gargantuan can have adamantine's hardness?
Or am I restricted to only animating adamantine objects the size of an apartment building?
I see that a GM can increase CR accordingly, but it doesn't look like a PC craftsman can make use of this. Or have I missed a rule elsewhere?
The monster descriptoins in the bestiaries are just examples. A GM could apply any template he wants, even make his own templates. Or just tweak the monster as he sees fit: "This particular orc is a supremely strong and healthy member of the orc race so I'm giving him +4 to his STR and CON. Just because." If he does so, he should consider how his tweak affects the CR, of course.
As for your animated object, you'll also notice that the CP you spend doesn't significantly increase the price of the object you're animating. For example, if you animate a wooden apartment building, it would cost EXACTLY the same price as animating an adamantium apartment building, even though you should have to pay a ton more gold to build that adamantium building.
You do pay a small price for the extra CP but that is a tiny fraction of the price of actually building the adamantium object.
Conclusion: using CP to magically give the animated object the hardness of adamantium does NOT mean it is actually made of adamantium.
Given that conclusion, it's reasonable to assume that the base stats for animated objects assumes the object is typical, made of typical stuff, then magically animated and magically imbued with CP that can magically alter its stats without actually changing the materials with which it was constructed.
And, finally, given that assessment, I would expect that if you animate an object made of non-typical stuff, you should alter the "base creature" stats BEFORE applying the magical benefits of CP. This can result in having to tweak the final creature stat block and possibly also adjusting its CR, but that's what GMs are supposed to do.
In short, if you spend the cash to make or acquire an adamantium broom and then animate it, it should have adamantium hardness. After all, you paid good money for that.
I believe the restrictions on CP are a lot more fluid than you seem to think. I see them more as guidelines to keep the abilities and CR of a creature in line with their HD (which is based on size).
So the reason why a medium object is allotted 2 CP is not because you can't have an animated adamantine greatsword, but because if you do have an animated adamantine greatsword you need to realize that it's harness and AC is going to be very different than is usual for a creature with it's HP, BAB, saves, and everything else that comes with HD.
Edit: Also, I see the CP system as more of a way to describe and give statistics to the existing properties of an object, rather than magically adding those properties on during animation. If one of my players wanted to permanently animate the aforementioned adamantine greatsword they would have to pay the extra construction cost for it to have the Metal:adamantine, and Slashing Attack properties.
As for your animated object, you'll also notice that the CP you spend doesn't significantly increase the price of the object you're animating. For example, if you animate a wooden apartment building, it would cost EXACTLY the same price as animating an adamantium apartment building, even though you should have to pay a ton more gold to build that adamantium building.
The adamantine building does cost significantly more than the wooden one. Remember, you need to have an object before you can animate it. The crafting turn-into-an-animated-object costs might be the same, but the initial cost of the buildings themselves most certainly do not.
Thanks for the insight guys. I've got a character cooking that uses Possess Object to occupy his brother's armor (his brother has unfortunately passed). This'll give me some perspective while sorting out how that actually functions.
Needing to buy Large armor for Mithral was kind of doable... Needing to buy huge adamantine full plate wasn't really in my grasp.