I needed a quick small rack for my 250g filament spools, to fit on the side of a desk.

There are two versions included, one for 12mm and one for ½" Aluminium/Aluminum tubing, depending on what is easier to get in your country. The rack can be as long as you want, just print more brackets if you think it might start sagging.

The brackets and the end caps are both printed in PLA, it seems to be strong enough for the filament I've placed on it.

The zip file contains all the separate .stl files.

Hopefully it's useful for you.