Hollow Coin

Circa 1950s-1990s

Still in use until the end of the Cold War, this was a common tool for all covert agencies to use, offering clandestine storage for microdots and microfilms. All you needed was a needle to poke into a hole in the face of the coin, to open up the two sides.

Just don’t forget which one is the fake one and put it in a meter.