I made a design wall from one of those cardboard cutting mats that you find at Joann's or Hancocks. I bought some flannel (on sale of course) in a solid color and covered the inside of the mat and stapled it around the edges to the backside. I like it because it is rigid and because I can fold it and put it behind a cabinet. If I need to take a WIP to class, I don't even take my quilt blocks or pieces off the design wall. I just fold the mat with the pieces on the inside and throw it in the car. The whole thing cost about eight bucks total to make.