I have a 24 x48 board on top of the adjustable height work bench. I found that 3/8 plywood worked fine. It is covered with one layer of insul-brite and one layer of the silver iron fabric. I have also made 24x24 and 18x 18 boards. On the smaller boards a layer of cabinet cushion is glued onto the back. This prevents the boards from slipping. I slide straight pins into the cushion and it holds all the layers just fine. You can hot -glue too.