Cut a disc from 3/4 inch plywood that has a radius of 2 7/16 inches. I turned it on my lathe, but a bandsaw or jigsaw will also do the job. Slice away nearly half of the disc, but leave the center. Drill a 1/4 inch hole on center. Countersink the hole for the nut and washer. Glue and/or screw a face piece onto the disc. Glue on some fine sandpaper, if desired, to prevent work slippage on the face of the miter gauge.