It's like Argo City's Omegahedron come to life: a 3D printer that can create metal structures in mid-air and that could one day be used to create electronics and biomedical devices that require custom architectures. It was developed by a team of researchers at Harvard's Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences, and uses no support structures at all to create complex 3D forms.
It uses an ink made of silver nanoparticles, which is hardened with a laser as it exits the extruder. The print bed is rotary, and the nozzle moves along three axes, which results in the ability to create swooping curved forms made of silver wire less than the width of a human hair in just a few seconds. These wires are also highly conductive. You can find the full paper in the early edition of PNAS, published today.