I couldn't find a spool holder that met the requirements for exactly what I was looking for, so I designed my own.

UPDATE: Added a bit more play to the rollers. Added a cap to the bearing stud to hold bearings in place. For best experience re-download and print the following:

Hnaging SP Roller Part 1x2 V2.stl
Hnaging SP Roller Part 2x2 V2.stl
Hanging SP Roller Bearing Stud Part 1 V2 x4.stl
Hanging SP Roller Bearing Stud Part 2 V2 x4.stl

Print instructions

I couldn't find a spool holder that met the requirements for exactly what I was looking for, so I designed my own. Three of the main requirements I was looking for are as follows:

1. Vertical hanging to mount inside my enclosure (rather than on top) and remove the weight from my printer frame.
2. Uses some form of roller or bearings rather than being dragged over a fixed arm like the basic spool holders.
   3.Designed in a way that a spool (especially new ones) won't unwind and tangle.

In addition it feeds straight down so if something jerks on the filament for some reason it's not going anywhere.

For flexibility I made it so it could be side mounted or an included adapter can be printed for a rear mount.

Printed with no supports

Rollers are easily removable to fit larger spools up to 100mm wide.

I would print at least 3 perimeters wide, my standard on prints is 4 bottom layers and 5 top. Infill was 20% gyroid.

It just barely fits in the printable area on a Prusa bed. You'll have to disable the first layer perimeter skirt so it immediately starts printing after the purge line.

Screws Required:
1 M3x12-14 Screw and hex nut for the top of the holder
4 M3x12 screws and hex nuts for the center loop
4 M3x12-14 screws for attaching the bearing stud

Optional 4 M3x16mm long screws and hex nuts required for the horizontal mount adapter.