If you are talking about a design wall, you can search and find lots of ideas on this forum. I used insulation board from Lowes and covered it with flannel. Mine is attached but there is no reason you can't just lean it against the wall. One note, take some pins with you to make sure the insulation board is easy to get them in and out of. A friend of mine used board that has a coating on both sides and it is very difficult to put pins in. Mine only had the coating on one side so I made sure I put the flannel on the side without the coating.