A near-clone of the following video (based on visuals and relative proportions only) as seen here: https://www.youtube.com/watch?v=EPCN8ifm7Ng. All credit to www.bonsaiwoman.etsy.com on the original design, I just wanted to surprise my partner with a copy of a thing that would take weeks to get in the mail and figured I'd open source the design.

Design modified to be quickly printable in pieces without supports and printed flat on the bed. Bottom face is designed with chamfers, top face has smoother-looking fillets.

The rod & spinner tolerance was set in a strange way (at an unusual angle relative to the starting axes) so you'll need to manually level the rod and endcap pieces so that the first layer prints fully. If your slicer has an auto-level on face feature, you'll want to click the long thin face on the rod (30 degree overhangs) and the bottom (open) face of the endcap. Make sure the chamfered side (see image 2) is facing the bed.

I took a pocket knife and shaved off any rough edges (and the remains of the brim) but a light sanding would work just as well.

I printed mine with a 5mm brim but if your bed adhesion is dialed in better, you probably won't need it.

I don't work with fiber, so this may require scaling up or down to fit your needs. I have a feeling the spinner will work better when it has a bit more weight on the end (printed solid?). There's another model floating around (https://www.thingiverse.com/thing:2409742) but that one requires a bearing and a piece of rod.