ecHi, I dont make foam boards but i do go to the dollar store and buy craft board that is paper on both sides with foam in the middle. It comes in s sheet the size of large poster. i just cut it down to the sizes i want to use. i get 6 to 7 81/2 by 11 inches pieces out of one sheet. So at $1.00 a piece for the large board makes my 6 larger boards that i cut out of it cost me 16 cents apiece. its very cheap. hope this helped you out