I have been reading through the replies but have not, as yet, seen this link which I came across as I was dreading the prospect of basting my next big quilt. I asked my son to procure two boards, but he decided to go one better and produced a collapsible frame with three boards, one for each layer. It works like a dream and I can store it behind the sofa!
http://sharonschambernetwork.com/index.html (go to the free area and you will find info for basting a quilt)