Pasty Thompson gives an overview of her basting wall design and use in Free Motion Quilting, Beginner Tutorial #2 found on this page of her website.
http://www.patsythompsondesigns.com/free-video/
I used two sheets of 2" thick rigid foam insulation for mine as I don't have it permanently adhered to a wall. I lean them at a slight angle against a wall in my basement but can move them to store between uses.