This is a laser cut spool for holding 3mm filament.
The spool is cut from 3mm Baltic Birch plywood.
If you're lucky you can just use the PDF file. Alternately there are DXF files you can use, or tweak things in the OpenSCAD files if needed.
Laser cut two plates and six spacers.
Once cut you can assemble with a threaded rod.
Put the rod into a drill and spin it to load the filament. (The spacers have holes to thread & hold the filament.)
The plates have 3mm holes so you can tuck the filament into them to prevent unspooling when not in use.