I bought a cheap Voigtlander vitomatic IIa with the Ultron lens to fix recently, but it was in such poor condition that this would have been impossible to do. Not wanting to waste it, I decided to try attempt to adapt its lens to use on my M5. The easiest way I could think of was to make it into a contax mount then use a contax to LTM adapter I have.
So here is the end result:
I used a mount from a Jupiter 8 kiev lens. Surprisingly the only extra parts I needed was a few screws and to make a DIY aperture knob. Luckly I could use the existing helicoid of the lens to adjust the infinity position, then I locked it in place with one screw. I think it's not too bad for my first attempt!