Remixed the original NinjaFlex design to work with hard plastics like PETG. Uses a twist and lock mechanism utilizing the two notches on the bare analog stick.
Printed with no supports, .15mm layer height, and 15% infill with PETG. Takes about 10 min on my Prusa mini.
To install, place the part around the analog stick so the two notches line up, push down, and spin it so it locks into place.
FYI the CAD is terrible because I made it in 5 minutes to put an end to a friend blaming the controller :^)
Original Design: https://www.thingiverse.com/thing:402795
The author hasn't provided the model origin yet.