Note: the photos show the first iteration of the parts, the design has already been adapted based on the shortcomings, but also not tested to verify they DON'T need slight manual post-processing.

There's already a lot of well designed spool holders here, but I was looking for a really simple one that uses very little material.

So I've made this design, which is printed in several flat parts and then assembled to hold a spool vertically, like a paper towel roll. It's based on my 3kg spool's need for 32m center.

The parts needed for use: 3x / 6x "Top Slice": 6x if you want to use 6x 608 bearings as "wheels", but it works for my 3 kg spool fine with just 3. 3x "Top Slice Plain": in case you only use 3x of the "Top Slice", print 3x "Top Slice Plain". They're the same, minus the part that holds the bearing. 3x / 6x "Axis Clip": Print as many as normal "Top Slice" you printed. Push a 608 or equivalent onto it, then into the bottom of a "Top Slice". 1x "Rail": so the spool stays where it is. Works just with it's own weight for my 3 kg spool.

Optional parts: 1x Top Link: just a small cage to keep the slices together, as their connection is mainly for alignment, not a "solid" connection. 1x Top 52m: adapter ring in case the spool you're using needs a wide center.

While I haven't tried it, it's likely possible to use this in the 6x bearing configuration with a 608-like printed "bearing".

There's also still a slight issue with the vertical configuration that I have not yet approached. If there's a long return of filament, like in my case my CR-6 going to max Z and back down, the filament will be pushed back so far that a winding of it will fall off the spool, which is a potential tangling risk. This has not yet occured during normal use however.