I stumbled onto this recently on eBay.
This first struck me as a bit silly and simply an exercise to show it could be done. As I think more about it, there are some lenses that might be worth the effort to refit to M body use. The seller also shows a number of other mount conversions but because I use Konica 35 gear, I was intrigued by the thought that certain focal lengths could be added for moderate cost to an M system with items that I already own duplicates in.
Not really knowing the exact needs for machining, especially the focusing coordination/framing lines, do you more experienced M folks think this is a legitimate exercise? Maybe this is a common activity and I never had reason to run into it before...? Thoughts?