This is a 3-part customizable spool holder for Bear Upgrade frame or any 2040 extrusions. 

Inspired by this model – https://www.printables.com/model/1019-bear-upgrade-spoolholder-snap-on-for-2040-extrutio

I wanted to have something modular. This model can also be customized to whatever fasteners you have, also it is possible to have a dual spool holder. See sources section below.

BOM

Default model uses:

• 40mm M8 bolt 
• M8 Nut
• 50mm M5 bolt
• M5 nut
• M5 washer

Also one of the variants available that only uses M5 bolts & nuts.

This model is fully customizable so you can adopt it to the bolt sizes that you have.

Instructions

• Attach spool holder to the spool with M5 bolt, nut and washer. Nut should slide in place inside of the spool holder
• Adjust spool to 2040 frame, and insert M8 nut from below
• Tighten M8 bolt until it grabs the nut
• Ensure that Nut, bolt spool jaw and main spool body are all aligned.

Sources

• Openscad models with different samples – https://github.com/avolkov/openscad-designs/tree/master/spool-holder