This is a remix of a remix from AdapWP (on Thingiverse).

It adds a hex pattern which makes turning it easier and adds some weight to the nuts.

I've also added various different lengths of the screw.

The screw is dual-threaded so both clockwise and counter-clockwise nuts will work on it. Best of all, the dual-threaded nut can turn both directions.

It's super fun to fidget with, and a good test of your printer's tolerances. If printed properly, the weight of the nuts is enough for them to slide on their own.