U.S. Army Research Office has just thrown some money the way of 4D printing—but what, exactly, is all the fuss about? This beautiful video goes a long way to showing us why the technology is so exciting.

The title '4D printing' is fairly slippery, but we had a stab at pinning down the concept recently:

In essence, the "fourth dimension" represents change—4D printing simply refers to printers that create objects that can transform over time and, in some cases, self-assemble.
This video, by Kinematics, give a flavor of what that can mean in reality. In its own words:

Kinematics is a system for 4D printing that creates complex, foldable forms composed of articulated modules. The system provides a way to turn any three-dimensional shape into a flexible structure using 3D printing.
The main advantage, as the video shows, is that shapes can be squashed right down into their smallest arrangement and 3D printed economically. Then, the structures can fold out into gorgeous, long, flowing arrangements.