I had about 40 feet of linear shelf space in my garage in CA. I took some 3/4" thick x 12" deep x 8 feet long pieces of plywood and cut a 1/4" grove into them from front to back every two inches or so. This allowed the boards to "sit" in the groves but not make contact with each other (or very little in some cases). It also worked great for being able to see what I had at a moments notice.