The one thing to be particularly worried about is if there are oils used in it's creation. I would try to look up the materials data on the foam and check. I've seen people using simple insulation foam like what's inside a fish or coral packing box. Maybe see if your LFS has some of that?
I looked everywhere for it. I had no idea how hard it would be to get it lol. I washed it out and it seems to hold itself togther no little pieces and it doesn't feel oily.