Summary

This is a compilation of three pieces I found in other spool hub designs on this site, plus a plug I made (scad included).

Print 2 hub inserts, and your choice of 2 knobs and/or plugs.

Hub inserts can have 608zz bearing inserted and held on 8mm thread-rod with knob+nut.

I prefer to use knob+nut, shimmed with washers - glued into hub directly (no bearing) and a second hub insert with plug+nut (again glued). 8mm thread-rod w/ spool affixed tightly, spins free-floating on my a-frame filament stand.

Printed at .25mm layer height, using ABS. Supports may be needed for hub insert - I use KISSlicer Pro 1.5 Beta (has very nice support options).
Glue I used is ABS slurry. Gorilla glue can be used if printing PLA.

Disclaimer: I collected most of these from others I found on this site - any rights belong to the original author (and their terms defined).