Here is a nerding attempt to reproduce a 120MM CCC shell case. Every once in a while I meet a collector that has cardboard tubes configured to look like a CCC case. Someone has obviously put a great deal of time in making these recreations and for all I know, they are factory made. They consist of many different size cardboard tubes fitted inside each other to match the dimensions of the real thing. I recently had to opportunity to purchase 2 of them (sightly different shoulder designs) in nice condition. Although they are really neat, and well built repros, I was not happy with the fact they looked so blatantly carboardish. I decided to turn it into a project and went to a local marine supply store and bought some fiberglass repair goop, like bondo. I gooped up the cardboard tube and smoothed it out to a smooth surface with tons of sandpaper. Here is how it came out with a AFT CAP mounted.
Bondo type stuff (really smells strong)
Finished product painted