Paul, I can appreciate conjuring up alternate uses for Plasti Dip. I have been mentally toying with a method of reskinning the rubber bumper guards on my '66 Satellite. I was thinking the spray wrap process, but they advertise that as removable. How did the Plasi Dip spray on? Would it hide checks and crazing in rubber?
Sounds like you are looking for a matte/low gloss black finish on your frames similar to what was used on some '41 and most if not all '42 Plymouth vent window frames. I picked up a black factory painted vent frame for my P12 to replace a badly rusted chrome frame - I am considering mixing Krylon matte and semi gloss black spray paint to get the right sheen, and airbrushing it on the chrome one (after prepping the surface) to match. If your frames are out of the car, powder coating is possible - more durable (and more $).