Nut and Bolt spool holder

The spool holder is meant to take 2 608 bearings, and an M8 threaded rod.

The larger the hole, the wider the spool can be for the same length of the bolt part.

Here's a video showing off the spool holder.
https://www.youtube.com/watch?v=0JIOuwceXqQ

These are the holders my spools mount in:
https://www.thingiverse.com/thing:1704669

The source for the files are here:
https://cad.onshape.com/documents/a37e35227e900fa4ad8ed71e/w/e3a5f48f5ff6cc9b3c0c1d79/e/c56aea0885f0ba7b7b47817e

And fear not, onshape while expensive for professional use, is free for public documents :)