VELCRO!! Use the heavy duty stick on kind. You can get the pre-cut pieces or get a roll and cut your own pieces. Attach one side of the Velcro to the wall, one side to the insulation board. When you're done, pull down the insulation board and store it. Leave the pieces on the wall. Buy a cheap flannel backed plastic tablecloth. Attach the appropriate pieces of Velcro to the top edge of the plastic side of the tablecloth. Instant removeable design wall using the same pieces of Velcro that you left on the wall!!