For placing into RigidBot bars to fix issues with stripped threads. I used a bar clamp to press the bolts into place. The large and medium sizes differ only in width by a fraction of a millimeter (the bars were somewhat inconsistent in size so I made two different versions). The small one is significantly smaller and I used those for holes that were further in.
Uses a 3mm nut with nylon insert (there's no need for to use nylocs, but that's all I had on hand). It will probably work with a regular 3mm nut too, but I haven't tried it.