awesome! I'd love to use mine on my M2...
Is it a permanent or reversible mod?
It is semi-permanent in that I Super Glue or E6000 adhesive to keep the RF coupler in place. Much force would be needed to remove the added metal RF coupler and any remaining adhesive would have to be cleaned off. In one of the four I used double-sided 3M tape so that one will be easier to reverse. The M adapter used is the one available from eBay. I just sanded it to remove the brand (Pixco) and give it the zebra look.
The metal part I use comes from an aluminum tube I found on eBay. It has a diameter slightly larger than necessary so I usually trim off a little bit. Here are detailed pics:
Typical steps in doing the conversion:
1. Check overall focus of the lens. I found that there is a little bit of variation on the infinity focus of the lenses. If possible I do not to modify the original infinity focus.
The infinity focus is taken care of on the adapter side.
2. Adjust adapter for infinity focus. The adapter from eBay is usually thicker than necessary so sanding it to the right thickness is the first necessary step. I do this with my Sony A7.
3. Unscrew rear element. Remove RF coupler.
4. Remove rear element from its housing. File and trim off excess thickness of rear element mount to make sure it can clear RF cam.
Glue rear element on the modified mount.
5. Cut off an aluminum ring about the necessary thickness. Cut the ring on one side and trim off excess to get necessary diameter.
6. Make a notch on the aluminum ring to match the screw. This ensures it stays in the right place. Use tape to keep it in place temporarily.
7. Try everything on an M camera. Make adjustments for infinity focus, then on close distances. Repeat until acceptable focus on all distances is achieved.
8. Glue the metal RF coupler in place.
The bulk of the work is filing and sanding parts into the correct thickness.