At your local hardware store you can have them cut clear acrylic or plexiglass to the size you want. After you do this, go a couple of aisles over and pick up a sheet of sticky back felt dots and apply them generously to one side of your new, freshly cut "ruler" (not so generously that you can't see what you are working on though). You can also use sand paper dots, punched with a regular hole puncher and a little glue. Either of these dots can be applied to rulers or templates you already own, as well. Good luck!