'Lazy Kate' bobbin unwinder for yarn spinning

The 'bobbins' fit on to our automatic bobbin winder (how fancy) so we can spin single strand yarn onto them. Then all three go onto the main central 'lazy kate', which is clamped to a desk/shelf, and the three strands can be spun together while slowly unwinding the bobbins. The friction is pretty much ideal - easy enough to unspool but enough that it doesn't unwind too far.

Onshape link if you want to tweak it: here.