These remixed parts provide a bit looser tolerance for the brake part mounting slot, and a bit thinner wall between spool bodies for wire spools that seem tight. Just in case your printed parts are a bit too tight like mine were.

I really like the remix "Spool holder box" by Azuzula. The "brake" provides just enough tension on the spools to keep them from unraveling, and the spools don't fall out. I also like the reduced part count and the 45-degree angled sides (to reduce filament usage and print time).

However, (possibly due to printer calibration tolerances) I was not able to insert the brake part onto the body tab of my printed parts - I needed just slightly more looseness on the brake mounting slot. Also, the spacing between body modules was a bit tight for the wire spools I was using - the spools were keeping the body parts from fully fitting together, and more friction tension was being applied to the spools than what the brake provided.

So, I tried modifying the STLs to change tolerances just slightly, for at least my printer. CAUTION! - I do not usually modify STLs directly, so I do not have the tools or knowledge to do this well. I muddled through, but the STL for the body did not cooperate, and has a flaw in the brake mounting tab that I cannot fix . I adjusted for this flaw in my loosening of the mounting slot in my version of the brake part, so my brake part seems to work fine with either Azuzula's original body, or with my modified version - at least on my printer.

I also punched a hole in my body part, to reduce filament usage and print time further. The STLs include two body parts (with thinner walls for spool tolerances), one with the hole and one without the hole. I use the solid version on the outside of the rack, and the one with the hole for the inside spools. You still need Azuzula's end blank piece for the other side.

For the brake part, supports are needed (I found Cura-generated supports to be easier to remove than the original part's built-in support).

I know these parts may not be perfect, and that others more skilled in STL mods could probably do better. But perhaps someone might find these mods useful.

Also, I did find that stacking these racks reliably can be difficult. So I designed a pair of legs to provide solid stacking of these modular wire spool holder racks. These legs are available at https://www.thingiverse.com/thing:5415292.