I made this because I did not like existing spool holder designs. They were either unstable/tippy when loading (easy to knock over) or not adjustable enough. This design solves both issues. So far it has been simple and reliable. Its been tested with 1kg and 5kg spools, and will likely work well outside of that range in both directions.

One of my main issues with other designs is they have a fixed distance between the two sides, or an extremely complex adjustment mechanism. By making each side completely detached and separate, you can simply move them to any width you want. Drag and drop. It cannot get any simpler. This can accommodate as low as 40mm wide spools up to infinity for that reason. I have no idea why other designs do this complex stuff with screws and sliders and unnecessary nonsense. Its like they are trying to build a Rube Goldberg machine!

The bearing backers are designed for heat inserts. They are like nuts embedded in the plastic permanently. You get a soldering iron and melt the metal insert down into the hole. That way you get the strength of metal in a plastic part. This print is designed for m3 screws. If you don't want to use heat inserts, you can print out 8 of the main bearing holders instead and just use wood screws or nuts and bolts. The only difference between the bearing holder and bearing backer is the size of the holes.

The specific STL files included here are for M3x12mm screws, and 608 bearings. You will need:

12 - M3 heat inserts

12 - M3x12mm screws

4 - 608 bearings. 608zz will also work.

You should print out 4 holders, 4 backers, and 2 floorplates.

If not using heat insertable nuts, print 8 holders and 2 floorplates instead. You will need longer screws in that case, M3x20mm should work if using traditional (not heat insert) nuts.

You can build your own parts using the parametric design on Onshape to make this fit virtually any configuration imaginable. Any bearing and any size screw. Just adjust the configuration options in the top left panel to change it around.

https://cad.onshape.com/documents/d61d8ca7ce51913cbcf9bd1e/w/afbe91f6fc42dda73865d398/e/85c559e100c4fb2eb28f421d?configuration=bearing_diameter%3D0.022%2Bmeter%3Bbearing_inner_peg_diameter%3D0.0078%2Bmeter%3Bbearing_inner_race_binder_diameter%3D0.0101%2Bmeter%3Bbearing_thickness%3D0.007%2Bmeter%3Bclearance%3D4.0E-4%2Bmeter%3Bfloorplate_length%3D0.124%2Bmeter%3Bfloorplate_width%3D0.04%2Bmeter%3Bheat_insert_nut_diameter%3D0.0043%2Bmeter%3Bscrew_clearance_hole_diameter%3D0.0032%2Bmeter%3Bthickness%3D0.003%2Bmeter&renderMode=0&uiState=69fdfea26df1e5ea28f9d629

This is public domain so you can use this for anything you like, even commercial use. You do not have to credit me.