I've heard of people making homemade targets using that instant foam in a can such as "Great Stuff" ,,i would like to make a fairly large target about a 32 gallon size,,i have a 32 gallon rectangular plastic garbage can that i thought i'd line with plastic to act as a mold release after spraying it full of the foam,,Has anyone ever tried this technique using the instant foam, and off hand would anyone know just about how many cans of that stuff i would need to do this or would it be about the same price or cheaper just to go down to my local archery shop and get theirs for about $15 (about a 2 foot square) is what the shop sells theirs for.??