Roll for my wall mounted filament spool holders

Some filament spools dont have a continuous flat inside surface. These spools then dont properly register on the bearings of my spool holder and therefore dont turn properly or sit on there crooked.

These simple tubes just slide over the bearings and produce a flat but rolling surface.Now all spools sit on there nicely.

I didnt even bother to model these in CAD, just two cylinders in PrusaSlicer. But they work very well. I printed them in Glowing filament because I can.