Spool holder for filament. To assemble the whole, you will need 4 bearings 608ZZ, which you must place in 4 holes in the bases. I designed the holes to have a diameter of 22.1mm. The bearings fit tightly for me, but you can use glue to prevent them from falling out of their places. I designed the rollers to have a diameter of 8.05mm, but there is a bit of play after inserting them into the central hole of the bearing. It's advisable to use glue to bond both elements together. After assembly, the maximum width of the spool that can be placed on the roller is 70mm.