So gorgo is of course correct about the task of replacing the base plate, but the real problem comes in from the adjustment method itself. If you look at the image below, which is the plate from a Slim Adjustable and more or less the same as a Fat Boy or other Gillette Adjustable... You'll see the nice square holes for the adjuster bed to enter the plate and hold up the blade, hence the adjustable part. Now in order to make an open comb, there's nothing that could be in that area for teeth to attach to. As a result even making a new baseplate you'd have to choose between open comb and adjustable. I'm sure the concept of an open comb adjustable is possible, I don't believe you'd be able to get there with the Gillette design. You could use the idea of machining or filing cuts in the bar to create a psuedo-OC model, but you still wouldn't be truly OC.
Hate to necro this this thread but does this count? All I know is it is German (from the instructions outlining how to adjust the razor for different beard conditions) , a two piece, and it has a spring loaded ball bearing in the knob that matches detentes of some sort in the barrel so you can run the knob down and then start backing the knob off in fixed increments. This lets the cap rise to change the blade gap... Here's a close up of the spring loaded ball bearing in the knob... And the instructions for our German speakers... Translates as "With this razor, the blade can be adjusted for every beard growth. It is also advisable to pre-shave with a tightened blade and to shave with a notch 1, 2 or 3."
David, I have no idea. There is no makers information on the razor or on the case (and its twin is the same way). The instructions are in German but these came out of France. I have seen one other example and it has the name Christofle on the inside of the lid of its case. Christofle, BTW, was/is a French silversmith company. They make no mention of producing safety razors.
