Soldering electronic circuits together sounds like tedious work. But what if it was as easy as doodling? A Japanese startup created a paper embedded with batteries and lights, and a pen that draws with a silver-based electric ink. The ink dries quickly and becomes immediately conductive. The video above shows you how it works. The company says applications of this ink are broad. It’s offering its printed circuits to various manufacturing companies that make things like 3D printers and lighting.