I saw a product at the Denver quilt festival earlier this month... I wish I had kept the flyer.. I gave it to my friend as I have a dedicated design wall.... Anyway, it's a box shelf that hangs from the wall, ( more like a valance...) inside is a retractable , like a window shade, reinforced felt design wall... you just pull it down , stick your blocks to it then roll it up when you're finished. genius.
here's another idea along that same vein...
you know those 3m adhesive hooks that you pull the tape off when you're done with the hook? Well, you make yourself a strip of 1x1 lumber, you can get 8 ft goods.. attach plastic sheeting ( or a painters tarp) to the lumber, then velcro to the back in several places, velcro to the 3m stickys up it goes when you need it , down it goes when you're done.