Take any binary image and “encrypt” it using a physical key card.

If you line up the correct key card with the encrypted image you can see the original image in the remaining holes.

You can encrypt multiple images with the same key.

potential uses

• ice breaker at party (find person with matching key card)
• secret santa like gifts (i.e. use key card as gift tag)
• …

It's not really meant as a secure encryption, it's just an example of a one time pad.

So please don't use it to build a highly secure doomsday device, or even better, don't build a doomsday device at all….

For a detail description and for the code to generate your own keys / images see here:

https://github.com/AlessioM/encrypt_3d