In the cylinder of the handheld device (which you can see in action here), three colored lights at different angles shine on the impression left in the metallic paint. Then, cameras arrayed around the tube snap pictures of the impression and assemble a table of color values. Computer vision algorithms then extrapolate from the patterns of colored light on the surface to a 3D reconstruction. The device can capture depths as small as a fraction of a micrometer, allowing printed letters, like these ones, to show up as 3D.