Bokode is a method MIT developed for tucking information (such as barcodes, images, etc. in microprint) into a tiny but easily visible package. It leverages the bokeh effect to show off the information on the microprint to anyone pointing a camera at the Bokode unit and defocussing. If you’ve ever taken a photo with a distant city in the background and noticed the city lights turning into little circular blobs when out of focus you’ve seen the bokeh effect.
If you’d like to follow along at home, Matthew’s site has the diagrams, laser cutter templates, sample patterns, and practical advice you’ll need to get started experimenting with your very own Bokode-like system.