Adjustable Small Spool Holder (Ender 3)

I've got some spools of filament, especially 250g spools - that have a very narrow hole in the middle, too narrow for the spool holder that comes with the printer.

I've used various hacks in the past, but wanted something a bit easier and nicer to use.

So, I found MadMange's excellent Small Spool Holder, which is exactly what I was looking for. I downloaded it, printed it, and then completely redesigned it from scratch :D However, it is still heavily inspired by the original. I've also taken note of the other two remixes and tried to incorporate their refinements.

It is a direct replacement for the supplied spool holder, it attaches to the bracket in the same way, wherever you've chosen to mount it.

The large nut is exactly the right size to be a "captive" nut, so you can tighten it one handed.

The small nut is just big enough to stop spools sliding off the end, but small enough to fit through a hole that's 30mm in diameter, so you don't have to remove the nut everytime