This is my wire spool. There are many like it, but this one is mine. In the process of reorganizing my workshop I needed to consolidate a bunch of loose wire and misc. spools; most of the printable wire wire spools on Thingiverse were either filament-heavy or didn't come in enough sizes. And so, here we are.

This design has two screw-on endcaps in multiple sizes, and a standard center shaft in several lengths. The inner diameter of the shaft is a hair over 1/2", so a cheap length of dowel rod or PVC can be used to store a bunch of wire conveniently. An OpenSCAD file is included, and can be used to generate endcaps with different fill patterns (circles, hex mesh, solid endcaps, and so on. It relies on the BOSL2 library for screw thread generation, though, so you'll need to grab it to customize things. See https://github.com/revarbat/BOSL2 for details.

TODO: Press-fit endcaps for dowel and PVC shafts, press-fit endcaps for paper towel and toilet paper tubes, click-lock endcaps for printers a bit too fussy to manage screw threads, endcap notch to secure wire-ends.