Spool holder for 40 x 20 V-slot

This design works with spools with holes from 45 up to 70 mm in diameter, which covers pretty much all brands of filaments available. It rolls super smoothly.

The design was made to fit both the nut on the nut holder and the bearings in the cones very tightly, so there's no need to use a screw to keep them in place.

Also using 4 bolts to attach it to the frame so it holds a lot o weight (tested with 3 kg and it was fine).