Inset for 2020 extrusion

I did something (https://www.thingiverse.com/thing:3978597) with printed 2020 extrusions like https://www.thingiverse.com/thing:2110950 and wanted to join those together head to tail. Just print an inset to fit into the holes of the extrusion and that should join them, easy.

Somehow thingiverse search didn't find me such a part and it was easier to create it myself. I included two length, 20mm and 40 mm but it is really redundant since you can define the length by changing the z scaling in the slicer.

Besides, the FreeCAD source is included so you can change it any way you like anyway.
I recommend to print it in a finer resolution so it fits better. It doesnt really need much infill, 10% was one line in the middle and the result feels very stable.

For some reason, when I needed it again the original version sort of fell through. And I wanted it really tight - so I scaled it up in the slicer and tried and tried again and when I hit 118 it finally was tight enough. So tere is the scaled version here as an update.