3D printer filament spool holder-feeder

Assembly manual video: https://www.youtube.com/watch?v=AycjpLIU_gA

This spool holder can be screwed to a flat surface behind or next to a 3D printer and feed directly into the printer or via filament sensor.
It uses two rollers on 4 bearings(19mm OD, 6mm ID, 6mm tall) So that the filament can be fed from the spool with minimum resistance.
The only hardware needed is: 4 bearings per each spool slot you need, and about ~5-8 short wood self tapping screws per each slot depending on how firmly do you want to attach it to the surface.

! not shown in the assembly manual video !
the dovetail joints that keep the parts together are pretty loose so they require some minor glue up, i used CA glue, but hot glue / construction adhesive or plastic hot staples would work as well.

The native version is 3 spool holder, but there is also a 2 spool version and a single spool version
If you want more, you can use the "Custom spool count" back connector and front wall to bind together as many slots