Yeah
We used styrofoam. Got the block at a company that manufactures architecture designs for buildings.
Poly is usually blue or yellow sometimes pink. Styro foam is the right stuff high desnity is easier to work. the guy doing the cutting has done it before you could tell so I assume he would have known.
I just wanted to be sure a guy who saw this and thunk it would be cool to cast the widget he was dreaming up knew too.
Wayne