I have had the problem of scratching my eye glasses with existing viewfinders so let me know if you have one for sale. I could really use it with my Retinas and Voigtlanders.
Note that most if not all of the Kontur viewfinders showed 50mm framelines, even though they were marked "35mm". They do work great though. After I had cataract surgery and received artificial lenses in both eyes, I could finally use my Kontur once again.