This model is based on dado jigs easily found on the web. After building one I found it nearly impossible to clamp in place. My improvement is integrated clamps held in place with quick-connect bolts. Each rail needs a slot so that the inner bolt can be tightened when working at the end of a board. I use a drill with a hex bit to speed clamp tightening and avoided the need for a wrench by soldering the nuts to large washers that have a pointed flange created with a chisel.