My husband and I just made a permanent design wall that is 8'x 8'. It could be easily made smaller and temporary. We bought four pink insulation boards(2'x8'), glued them on the basement wall and covered by batting. Cost total for the foam boards, concrete to foam adhesive and batting $75 - 85. I have a smaller portable design wall that is 48"x48" made out of a pink foam insulation board cut in half and held together using duct tape. It is also covered with cotton batting, and the cost was $0 since I used the stuff we already had, but it would be about $20 if you we're buying the supplies. The cheapest method by far is buying a flannel backed vinyl tablecloth and pinning it to your wall.