When I first got my '95 Corvette, I purchased a cup holder from one of the aftermarket suppliers.  My wife was never completely satisfied with it because it stuck out too far into her leg room.  After seeing how the aftermarket model was mounted, I decided to make a new one from some 22 gauge sheet metal, sticky felt material, plastic door edge guards, and two folding cup holders that I have used on my 1990 K-Blazer.  You can see the results in the following photos and how it mounts without any drilling of holes in the Corvette.  I mounted the cup holders to the holder with pop-rivets.  I also used a metal bending brake to bend over about 1" all along the long edge for added strength to that smaller supporting part of the metal that goes all the way to the floor.

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