john_s
Subscriber
This is a great idea! I used SKGrimes' contact us form to check on how much it would cost to machine a Copal #0 to SL66 adapter.
I also have a broken 127/4.7 Ektar that I've been meaning to send to KEH to have worked on but just haven't yet. I might try that one as well.
Off the shelf, the adapters have a small pilot hole, and the plate is then drilled and threaded. They are available from time to time on ebay (include world wide in your search). You probably have to be patient. You might even be lucky enough to find one that's been threaded to the size you want. There are various other SL66 adapters, rings etc that might be usable with a bit of work.