I used 4x8 sheet of styrofoam from Home Depot. Cost was $6.99 used paneling nails to tack into the drywall, no major damage if it needs to come down. Then pinned an inexpensive vinyl tablecloth flannel backed, the cheap ones from dollar store. $2.00. This way I can position my blocks, and I do a lot of quilt as you go panels, then I can pin through the styrofoam to carry the weight of the panels!