Most woodworkers know to insert a protective pad between the workpiece and the metal jaws of clamps to prevent marring. Unfortunately, it often seems like you need three hands to hold the pads in place and tighten the clamp. This keyhole pad design eliminates that challenge.Start by cutting 2 x 2" squares from 1/4" plywood. (Each pad requires three such squares.) Cut the U-shaped openings in two of the pads, as shown in drawing. Glue the three layers together and clamp them with spring clamps. To hold the pad in place on the clamp, cut a retainer block to fit snugly in the larger opening. Tap it in to keep the pad in place; tap it out if you want to remove it.—Bob Youngquist, Columbia, Mo.