This is a quick and simple clip for holding t-nuts in place in 3030 extrusion that I made as an assembly aid. This was designed for and tested in Misumi HFS6-3030 extrusion. Simply press the clips into the slot where needed or slide in from an end. They should be a snug fit but move without too much effort.
Most of the clip is only two layers thick (if printed with a typical .4 mm nozzle) You can print it solid or just one layer thick if you want. I've only made with PETG, but should work with PLA or ABS.