I used flannel. I have 2 boards that are 4' x 8' that I sprayed adhesive on, then covered each with flannel. The boards have a groove in them so that they will push together, then I use "U" shaped long floral pins to keep them together when I'm working on a large quilt. Pushed together and pinned, I then have a board that's 8' x 16' so that I can pin larger quilt blocks onto. If I'm having an event or need to take the boards down for some reason, they are easier to store because they are separate.