Inspired by many filament spool holders on Thingiverse. This is the one I ended up using, for now. Design made with OpenSCAD. Requires cheap ball bearings for skateboards like those:

https://www.amazon.de/gp/product/B00WXDAUQG/

Print instructions

Printer Brand: Prusa
Printer: I3 MK3S
Rafts: Doesn't Matter
Supports: Doesn't Matter
Resolution: 0.15
Infill: 15%
Filament: Prusa PLA Silver