Remix from https://www.thingiverse.com/thing:2285502 All credits to the original creator.

Slightly modified the mountingplate to be able to attach it to the 2020 extrusion.

Made it wider and 5mm thick. There are two versions of the mounting plate. One with and one without the 5mm holes.

I added the split in hal version of the 5cm as well.

These are easily printed them lying down without supports and stronger this way.

You will need 2 of them and glue them together during assembly with superglue or so.

Assembling the parts was easier this way too, as the ball joint is a very tight fit.