Magnets keep your clamp pads in place
Recess small, round hobby magnets into 2" squares of 1⁄2 " plywood. Drill the recess holes just deep enough so the magnet projects slightly above the face of the block, then epoxy the magnet in place. The magnets hold the blocks on the clamp jaws while you're clamping.
—William M. Resnik, Albuquerque, N.M.