I use styro foam but its not easy to work with. I have destroyed alot of peices before I learned to not over cut it. The smaller the foam balls the better (meaning tighter styrofoam). large foam balls will look to much like styro foam and will require alot of paint. Never spray paint styro foam it only melts it.

__________________

Whos Da Masta

http://www.youtube.com/watch?v=jrXSWI0oWHg