I use brass tubes sharpened using a #11 razor blade, and spin the tube by hand to cut balsa . For plywood I cut little teeth into the tube and stick the tube in a drill. The edge has to be re sharpened after cutting several holes. I saw this concept of a tool for sale by one of the RC company's at the LHS. I think it was $10.00 or so, it comes with a knob attached to the tube and an inner rod recoiled with a ball point pen spring to clear the plug from the tube. I use a piece of metal rod to poke the plug out of the tube after each cut.