This is a 3D-printable version of a bobbin for the Electric Eel Wheel Mini by Dreaming Robots. I designed it so that it doesn't require supports, though the trade-off is that glueing it together takes a little more care.

Print one of each file to make a complete bobbin.

This Thing has now been tested and worked great for spinning! v2 has relaxed clearance, and may fit a little loosely, but is good if your printer fully tuned in. v3 has tighter tolerances, and consists of only two parts for faster printing and easier assembly.

LulzBot

Doesn't Matter

0.25mm

Coarser settings may work; I designed it around 0.25mm layer heights and printed it with a 0.5mm nozzle. Anything smaller should work, too.

Print one of each file per complete bobbin.

Post-printing, you'll have to glue the pieces together (this was preferable to requiring supports). To reduce drag, there's just a little bit of trickiness to assembly.

Glue the flat end of the bobbin to one end of it, pressing the hub down into the end. This can be flush with the end of the hub, since the flyer has a small contact surface with the bobbin

Then, repeat on the other end with the pulley end, making sure that the small side of the pulley end is facing outwards, or downwards on the table when you press the hub into it. This time, to reduce drag, place thin spacers under the end on either side so that the hub ends up sticking out just a little bit (0.5-1mm, if possible; 2-3 stacked business cards should do it). Since the EEW Mini has a flat wooden frame, this little inset reduces the contact area and friction to just the end of the hub.

It's also a good idea to sand the ends of the hub after printing to make sure they're smooth. You might also scrape the inside of the ends of the hub to make sure they're smooth, too (the offset a little ways in helps with the rest of the tube). If desired, you can also wipe a dab of Super Lube synthetic grease with PTFE on the ends of the hub (other synthetic greases should work, too).