You could also use baltic birch which you can find at Home Depot and ask it to be cut the size you want.
Also I have see lots of left over acryllic that are the rements of using the acryllic for something else.
One time I had 5 rulers cute various sizes that were common, like 2 1/2 3" 5" 6" etc. when i lived on Cape Cod. A gentleman had made a whole bunch of them for Heartbeat Quilting. They worked great. Lynne Plotner Pierce
Surrpise AZ.