Cutting nut slots ( the slot for the nut, not the slots in the nut for the strings ) has always been a pain in the ass. I've done it with the table saw, with the fret slotting jig, and freehand with a file, and it is always more adventure than I like. There has to be a better way, and this contraption is it. ( The gray clamp is not part of the jig, it is just there to keep the router from tipping off. )