Funny this should come up; I thought about posting my design board this morning but didn't know if it would useful or not. This is how I lay out blocks; once the blocks are done, depending on the size of the quilt, I put them on a large piece of Warm and Natural that I have hung on a wall - or if that doesn't work, I lay them out on the floor, lol.
As I was making large blocks (15" from Bonnie Hunter's "Easy Street), I used a large piece of foam board I had, cut it down to 20" x 40" and scored it at 20". Originally, I covered it with Insulbright that I had as after hearing horror stories of it catching fire in the microwave, I wasn't going to use it for the original plan. I used a hot glue gun to adhere it. Unfortunately, I found that my pieces didnt really "stick" to it, it's too smooth. So I peeled that off and used a piece of Warm and Natural I had. When gluing, I run a little glue at the edge of the top, about 8" at a time, first one side, then bottom, other side and top, smoothing as I went. Then fold it to the back and repeat. This works great for me; I set it next to my sewing machine on a small table that I also iron on; I put together two blocks at a time. Sew one, turn board around and do another. Works great for me!