QR codes, those goofy black-and-white arrangements of digital information, could help secure bank notes. Scientists just showed that they could print an invisible QR code made of a high-tech ink ...

3D printers are great for creating static objects, but if you’re clever, it’s possible to print functional devices. If you’re absolutely brilliant you can go far beyond that, which is the case here.

Our lives were made considerably simpler by QR codes, which were developed in 1994 by the Japanese vehicle company Denso Wave. QR codes often include data for a tracker, location, or identification ...

Cody Wilson with 3-D printer gun plans in Austin on May 4, 2015. Wilson is engaged in a legal fight to distribute plans for printing 3-D weapons. (Ilana Panich-Linsman/The New York Times) Cody Wilson ...