I use plexiglass. I went to Lowe's and grabbed the largest sheet they had. Its cost was just under $20 at the time. I had premapped how I wanted it cut and the cutter did an excellent job cutting 10, 10 1/2, 11, 11 1/2, 12, and 12 1/2 inch squares for me. She also cut one of the left over pieces in half (ended up about 2 x 18) and when I got home, I glued the two "exacts" together. That one I use with my long arm. The squares I use to "square up". I also got the drill out and put a good sized hole for hanging and took a permanent marker and drew lines x and + on each one. It is so easy to align. I got a lot of straight edges out of the sheet! I actually have thought about going back and creating a 6, 6 1/2, 7,etc to 10 to finish the set.