Elmer Foam Boards are 1/4" thick and are 20"x30" they have foam in the middle and a plastic coating on the outsides. I use three in a row and duck tape them down to the table. This enables me to build a 90" wing in one piece. They are flat and stay flat. They are in the craft dept. at Walmart for under three dollars. I usually get two builds out of each set. Ca glue just wipes off the shiney plastic coating and they hold T-Pins firmly in place. Masking tape holds well for your plans and wax paper, but comes off easy when your done. After you remove them they make a great cutting surface for razor saws and X-acto knifes. Hope you try them. My wife brought them home and said why don't you try these so I did. I wouldn't use anything else now.

Gibbs