If it's a weapon make some materials.
If it's got an intelligence score, and is an item, it's an intelligent item.
Otherwise it's a construct.
If you're holding a cat and saying pewpew then it's not a construct.


For living material, you could just replace all gold cost with food of equivalent cost, for instance you could replace ammunition or repair cost, I wouldn't require the player to feed the object every day.
I'd also leave the fluff open ended, what it looks like, what materials are needed to feed it, if it eats or subsumes or is injected, ect.

It seems like you're setting up camp for the long haul here though... I'd move this to gramarie, those guys looooove long haul.