I just used foam board but cut them up into kind of L shape with a curve. I did that by first cutting out a rectangle block and then drew a curve shape for the L on the block to cut out and then sand. After that , you can just use the original cut up block to make a bunch of others. They won’t all come out exact, so when you finish cutting out all eight pieces, be sure to sand them together to as uniform as possible. It’s extremely tedious, but the result looks pretty good.