Saw Koepenick55's gimmick for holding boxes open and thought of modifying it to something to assemble wooden - or MDF - boxes using butt joints with screws or dowels and glue. I designed one for 12mm MDF sheets and one for 19mm, the actual openings are 0.5mm less, so the panels are held tightly without one having to use excessive force to push the clamps onto them. I use these mainly for predrilling screw holes. Included are 2 clamps to assure drawer slides can be mounted flush with the front of the drawer.