Note Print with supports at 0.12mm if you can, 0.28 is stronger but has worse "resolution" if you care about looks. Print at 50% infill and above. 100% doesn't really add extra strength. 

Replacement for the Nutribullet "magicbullet" couplers.
Mine lasted the better part of 10 years, finally gave out.
I ordered replacements on amazon, they both broke after a few days of use. The plastic is brittly, and for whatever reason the shaft extends enough out of the top for the top of the plastic (on the coupler) to pop off. Eventually just tearing the whole thing apart form centrifugal force.

I got two designs. One with no top but a plug, to stop the pop from being the failure. This however makes it less resistant to centrifugal force, So should only be printed form materials like carbon fiber reinforced nylon or PETG for example that arent as brittle as PLA.

The other design, is just like the original. it should be the best one to print, without a hole in the top as the PETG or Nylon can flex a little bit. PLA can be used here aswell but i reccomend printing out "top gap" that has a 1mm wall instead of 2mm at the top for a bit of "play" there. 

All of these need the original brass nut you can source from your old coupler by breaking it or heating it up and removing it. If not you need an appropriate heat set insert. That has a diameter of about 12mm (outer).

Has lasted me a few weeks so far (i use the top gap version). Printed in CF PETG. No significant wear so far after using it. [03-12-2025].