Going totally into useless nit-pick mode (although it may save you some confusion at some point):
Expanded bead foam is the (usually white) stuff that has identifiable beads in it. They get shipped to the factory as compressed beads (with, I assume, adhesive on the outside), blown into a mold, and then heated.
You're looking for foam, and closed-cell foam* to boot, but not expanded bead.
* Closed-cell foam is foam where the little bubbles haven't popped, so the foam does not absorb water or whatever. The other kind is like celulose sponges, and I have no clue how you make not-closed-cell foam, or what the proper term is for it (open cell?).