The title is not descriptive enough. We are talking about world record sizes. A 3D printer in the Viena University of Technology can print a model only visible though a microscope, since it is in the size of micro meters (um) in record time. The printer uses the two-photon lithography method.
The 3D printer uses a liquid resin, which is hardened at precisely the correct spots by a focused laser beam. The focal point of the laser beam is guided through the resin by movable mirrors and leaves behind a polymerized line of solid polymer, just a few hundred nanometers wide. This high resolution enables the creation of intricately structured sculptures as tiny as a grain of sand. 1CUntil now, this technique used to be quite slow 1D, says Professor Jürgen Stampfl from the Institute of Materials Science and Technology at the TU Vienna. 1CThe printing speed used to be measured in millimeters per second 13 our device can do five meters in one second. 1D In two-photon lithography, this is a world record.