Summary

A spool holder that fits in a cereal container. Details at: https://tomhorsley.com/hardware/corexy/spool.html

A pair of the rollers from https://www.thingiverse.com/thing:2047554 fit in the slots of the inserts in the bottom of the cereal container.

Openscad files are provided to adjust the slot width for different size spools you may have. The ones for the Hatchbox spools I include in here are probably for an ancient spool width no longer in use. The Octave spools seem likely to fit many other brands of filament these days.