I bought this mounting plate in a hardware store and designed the holder so it fits the holes on the plate perfectly. For the connecting rod I used a wooden stick of 27 mm in diameter (I bought a handle for a garden rake and cut it to the right dimension).
I have the mounting plate mounted vertically, so the distance between the brackets is shorter. For longer distances you should insert an additional bracket in between.
I also made some end caps, so the wooden rod doesn't slip and fall.
I printed this on:
Creality Ender 3 pro
Infil: 20% +
Shells: 4
Layer height: 0.2 mm
PETG
The author marked this model as their own original creation.