Michael, it's not too bad. Mauser figured out that only 1 part needed hand fitting before blueing, and numbered these parts (rear toggle part only) in order to assemble them on the right pistols. The serial number is electropencilled on the bottom of the rear toggle as a result.
An exception are the pistols that were factory chromed (matte hardcrome plating). Because of different tolerances (adding a layer of chrome plating), these parts were numbered to the gun (only those essential to function properly).
So you can do one, and still have the other. The 1965 prototype (basically an 06/29 without grip safety) was sold to Mauser together with the plans and some sample guns. It ended up in Prof. Dr. Rolf Gminder's collection, and has moved on since. We used photos of the pistol that came from Gminder's archive for our book.
I think the Mauser engineers, and the companies involved, deserve a little more respect. The main reason that it wasn't popular in Switzerland was because of other, economical, issues. But that is another story
