It seems that you and I might speak the same language. I'm an engineer at Boeing in Seattle and I'm very familiar with CAD/CAM techniques. I also happen to be in need of a Falke 90 rear sight. Tell me. which country are you based in? I came to the US from UK some thirty two years ago, but I still collect European air rifles. I'd be please to support your effort in any way I can and I can lend you a good sight from my other Modell 90 as a pattern. I might know a source for CNC machining over here, however, I do not know how competitive the US shops are these days. Pity, I was in and out of China last year and I had good manufacturing contacts then.
So anyway, welcome to the the forum and let me know if I can help.