Summary

It's a x-shaped filament spool stand for bearings with an axis diameter of 6 mm. The distance between the sides is adjustable to any spool width up to 100 mm. The distance between the axes is 120 mm for most stable stand. I also added an alternative version for screw mounting the bearings (because I had some issues with the stability of the click axes). The knob can be glued to the rod, if it's too loose.

For the white pulleys I used prefabs, they are not printed. Basically plain bearings shoud work with this design too.