I once sent in some box tops and got back a gelatin based reproduction device. You’d put some sort of fluid on it, and build your original document, and run off copies.
A gadget freak since birth, that thing fascinated me.
I was big-time for about a day, until the concept grew tiresome.
“:^)
Aw, those were the days.
We used that in school when I was a kid. Gelatin in a cookie sheet, then indelible pencil to make original, soak original on gelatin tray wet it down. After indelible pencil soaks into the gelatin begin copies by placing paper on gelatin and wet it down. Remove copy and hang to dry.
Those were the days. Unless you got suckered on the Super Secret spy telescope with a secret code sender ring, you haven't lived.