I got a piece of "foamular" from Home Depot which is a pink styrofoam insulation board the size of drywall sheets. I've found it in 2 different thicknesses (about 1 & 2 inch). I covered it with muslin (to cover the color) then a piece of felt. I pinned the fabrics all around the back edge. Mine are about 4x5 feet and I move them around the room but if you had a free wall you could mount it to the wall. It works great. The fabric sticks to the felt and I also use pins to pin up freezer paper templates.