M5 Square Nut Holder for OpenBuilds V-Slot

During the build of my J-Bot the M5 square nuts often left damage on the v-slot when over tightened. They were also difficult to start to thread if the M5 screw wasn't quite long enough or if the nut wasn't sitting parallel to the face of the extrusion. These inserts help prevent both problems. The only negative is that they must be inserted from the ends of the rail.

Ultimately I think the pre-assembly t-nuts are probably the best way to go, but if you already have the square nuts then th