It's extension for Mega Anti-Tangle Spool Holder (https://www.thingiverse.com/thing:2479238)
Once upon a time I got a 2kg filament spool which didn't fit on my printer, so I decided to rewind part of it on some old 0.5kg spool - but it was a nightmare.
This is designed to work with a high torque motor (like this: https://tinyurl.com/y5vynevg)
and powered by H0 electric train power supply to manage the RPM.

JGAurora A5

No

No

0.2

10

I made it some time ago so I can be wrong, but if I remember correctly - only the bolt is printed with support.