Mine is about 4x6 foam board with batting and a flannel sheet. LOVE IT. When I'm not using it I just put it behind a dresser. I also have one that's about 20"x20" that I use on an easel for block layouts. The foam board is very easy to stick pins in if something is heavy. It's about an 1" thick and I got it at a local building supply store. You can also make them out of those folding cardboard cutting mats, a couple of curtain rods, large clips and some flannel.