Reptile safe/heat safe scuplting clay?

[TheresaB.C]

Hello. I am going to be making my leo a custom cage interior pretty soon and i am researching materials at the moment. I am going to be making a Lord of the Rings cage theme and I want to make the ent forest. I plan on making one of the ents but I can not carve it out of foam as the mortar coating later will take off all the details. Are there any none toxic heat safe clays out there that I could sculpt it out of?

To give you an idea about the level of detail i need, here is a reference of ents.

 

[CWilson13]

While it would take more research, I think sculpey brand polymer clay might work. It says non-toxic but that is for humans not reptiles. I know that it is very durable under heat, especially after it is baked and hardened. Again, just a first thought suggestion though.