Some years ago, I inherited my aunt's Argus C-3 camera set. I didn't know what to do with them because I had my own Pentax system. The set stayed in a box in my closet for years. I also have 4 different Pentax cameras that I not longer use, now that I have my K-1ii digital. So what to do with all these cameras? I could try to sell them, but they would not bring in much money and it would be a hassle. Besides, each of these cameras have special memories associated with them. So instead, I decided to display all of them in my house.
So on the top, you have my aunt's C-3 setup. She got two identical cameras (why? we don't know), flash, a meter, and a lot of other little things. I put them together in this aged wooden display case.
As for my Pentax cameras, I just put them all on a separate shelf below the Argus setup with a common (read cheap) lens. For the Pentax, I go from a total manual camera (K-1000), to an auto exposure camera (Super Program), then add auto focus (PZ-1), and then on to digital (K-30). I owned all of these, although I admit, I sold the Super Program years ago (but recently bought a non-working model to display).
So now I have a display of 35mm camera from the 1940's up to the 2010's, over 70 years of 35mm photographic equipment.