I modified a Canon to accept the Leica Noctilux 50mm f1 Leica lens back in 2012. I couldn’t afford the M9 at the time, and wasn’t sure I wanted to afford it, so I decided to cut into a Canon 5dmk2 and modify it to accept Leica M lenses; all of them.
The modification wasnt easy; nearly impossible unless you decide to dedicate weeks to learning how to do such a thing from scratch. For the modification, the camera was completely dissasembled and the mirrorbox was removed and stripped of its components. The mirrorbox was then machined by a precision machinist to the correct flange distance for Leica, 27.8mm. That number, 27.8… after months of obsessing over doing this, that number will be permanently etched in my skull.
The mirrorbox was reinforced with a two-part plexiglass frame. It is further reinforced with a 3mm thick piece of steel which serves as the lens mount. As a result, the mirrorbox is more durable than when it came out of the camera, and strong enough to hold even the weirdest, heaviest rangefinder lenses out there, from which there are hundreds.
blah blah blah… anyways it was an obsession, I learned alot about the inner workings of a DSLR, and used it to make some interesting pictures. Then I sold it and moved on.