Making a signature stamp - GIF

[bruce.desertrat]

The round-grayish material is a a polypropylene foam that allows the ink through. The desired stamp design is drawn or printed onto a mask material, then the machine (which is basically a very high-powered photoflash) essentially melts the the surface of foam anywhere the mask isn't, so the only part of the design that admits the ink is where it was masked off; basically a form of photolithography.

Weirdly, I was able to find a decent description of the process in, of all things, a mechanical engineering scientific paper about fabricating MEMS (micro-electromechanical systems).

The weird rabbit holes these posts send me down....