I have a lot of experience building things out of styrafoam from playing wargames. I want to know if its possible to make hides for my snakes out of pink insulation foam and then cover them in something to make them safe? I have seen rock walls built this way but dont know what they were coated in. Some plumbing putty stuff I think. Does anyone have any experience with this? I could build custom sized caves.

Also if this doesn't work what about a safe air dry clay and safe paint to make my own caves? Does anyone have any ideas? I like natural looking hides but don't want to pay the price for the stuff at work (Petsmart)