Focus gear to use with Canon 50/1.8 II lens and DJI Ronin focus motor. The inside has a small chamfer (65-66mm internal diameter) so only goes on the lens in one direction.
Depending on your machines tolerances, you might need to sand the inside a little bit, or use electrical tape or something for correct fitment. I used thin electrical tape so it won't slide of (as the lens' stock front is plastic).
Alternatively you can print this from TPU, and with a tighter fitment it can be great for push-fit.

STEP file included, feel free to modify it for a better fitment.

If you need something similar for other lenses, feel free to contact me.