This is a adapter to allow your filament spool to easily rotate on a rod.
You can adjust many of the parameters and dimensions of the spool bushing in the .scad file or Customizer.
The .stl files have the dimensions for a 32mm spool mount and 8mm rod.
The printed bushings in the pictures were my first attempt at the design, but after cracking both bushings, I made the walls thicker and added several improvements to the design.

Print two of these and push them into the holes on your filament spool while they are still hot.
I prefer ABS, but PLA works, too.
There are instructions in the .scad file on editing the parameters.
If you make one, please share it under the "Made" tab!