Actually, I can't take credit for this. We needed a tool to sand the milling marks on our knob recesses and Steve said "to bad we don't have an old exhaust valve or something". Well heck, I called the machine shop around the corner that we've known (and worked with) for years and Steve went over. When he told Rick (the owner AND guitar player and hobbiest builder) what we needed he milled a scrap valve to the size we needed.