Bruce from the E3 club introduced the sleeve adapter for the spool holder he found on Thingiverse. It was tweaked in a number of ways.

1. The design fits the Ender 3 post but was too big for the Killer class machines we have so  a thickness ring was added. The original design stl was imported into Onshape and the ring was added.
2. The thread form was traditional 60 degrees. When printing this sags in one direction.This didn’t make it super easy to spin. The sleeve was redrawn in Onshape with a round semicircle thread form. All parts were adapted with a semicircle thread form.  A lot of turning is required when you have a large opening in the spool hub.
3. The “spikes” on the wedge portions of the bolt and nut were hard on the fingers. A more relaxed ergonomic design was developed.
4. To minimize the amount of turning a split thread was developed borrowing from wood vices of the past.

The four parts are shown here.

Note the semicircular thread form in the section view here.

Parts were printed in PLA on various Ender3’s. 

My friend Dave is an astronomer and was intrigued by mechanical Orrery’s and especially one that could be 3D printed. This one was found on the internet. The idler gears in the original design were two separate gears with a pin to connect them. The pin was made as part of the print on one gear. The pin is a crossed boss into crossed slots on the other gear. Various other tweaks for smooth operation. 

Parts were printed in PLA on various Ender3’s.