Love your organization and sewing room.
This is the Dollar Tree website page for the Readi-foam boards. They are a $1.00 each and you can order a case for $50 from the store or online. I just used an 8 1/2 x 11 sheet of paper as a template and drew a line around them on the foam board to cut out the fabric boards. I cut them out with a hobby knife. You get a ton of fabric boards out of a case. Very cost effective.
http://www.dollartree.com/classroom-decorations/classroom-decorations/Readi-Board-Foam-Boards/809c809c809p16450/index.pro?method=search