At the art supply store, it is possible to purchase "Foam core board". At the better art supply stores, this comes in 3 X 5 sheets. Great for design walls and it comes in 1/4 or 1?2 inch thick. It also works on a table in place of plywood for pinning. You can try one of the small pieces to see if you like it. the larger pieces cost less than $10.00 and weigh a fraction of plywood.