PTFE M4 threading tool

So I want to use M4 nuts for attaching PTFE tubes to my extruders, I've had few broken PTFE couplers when doing multi-material printing with strong extruders. But one thing has always been a bit cumbersome and that's getting the nuts thread to the tubes. It's quite hard and frustrating to get the nut to start threading properly and straight. So I made this little helper tool that makes this task easier.

OpenSCAD source in github: https://github.com/spegelius/3DModels/blob/master/Multi-material_feeder/Multi-material_feeder.scad

1. Print the part. The printed cap should thread to the tool part, if not there's probably issues with the tolerances. Tune slicer or the source.
2. Inset a M4 nut into the tool nut slot
3. Screw the cap on to hold the nut in place
4. Feed PTFE tube in to the bottom of the tool
5. Push and rotate the PTFE tube to thread it in to the M4 nut (protip: use paper towel or cloth for better grip)
6. When nut is threaded enough, unscre the cap and push the PTFE tube to free the M4 nut and pull the tube from the tool

As the PTFE tube compresses with the nut, I use 2mm drill bit to open it up.