This design is a spool holder conceived to be compact, low friction, accommodate all types of spool and easy to attach to any aluminum profile.
It uses 3 bearings 624 (4mm bore, 13mm outside diameter and 5 mm width) and attaches to aluminum profiles with two T nuts.
The bearings, fixed with 3 M4*20mm screws, run into an internal groove in the "part 1" piece. The "part 1", "part 2" and screw part attach together around the spool and rotate freely with it.
The screw length required may vary depending on your spool. The file "screw long" should fit most cases but you can use "screw short" for spools with particularly large diameters or small width.
The groove in "part 1" is the most difficult feature to print and the only one that require supports. The friction in the mechanism can be strongly increased by a poor print.

Please refer to the YouTube video here for more details:
https://youtu.be/tO8IoAOTpAA