Someone stopped by searching for “how to make paper shotgun wads.”
Well, the tool used is called an “arch punch.” The inside diameter of the punch should be the same as the inside diameter of the shells you are using. And you use the arch punch to punch out wads out of suitable material. In those days before TV punching wads and rolling your own shells was a good way to pass a rainy afternoon.
The material for the first layer over the powder, the overpowder wad, is very stiff card stock. Back when pressboard was free for the asking at any small town newspaper I used a lot of it for wadding. But basically, any stiff stock between 0.20 and 0.40 thick will do.
The next layer in store bought shotgun shells was a thick, fibrous paper that was made for the purpose. I used to use several layers of the heavy waxed cartons beer was shipped in for wadding, and dispense with the overpowder wad, but that was laziness more than anything else. You will probably have to hunt up a suitable wad material for your application, but discs of thin cellulose ceiling tile would probably work very well.
The thickness of the wad column was chosen to allow the desired weight of shot, plus the overshot wad, to bring the overall height to the proper height to be crimped. And yes, sometimes you had to either add or subtract shot to bring everything to the right height.
After the shot was dropped in the shell, the overpowder wad was put in and the shell was crimped. And the next step was to call the dog and head for the field or blind.