World's lightest material: Metallic microlattice

        Metallic microlattice is a metal developed by a team of researchers from University of California at Irvine, HRL Laboratories and the California Institute of Technology. As shown in the picture, the Metallic microlattice is resting on a dandelion fluff without damaging it.
       With a density of 0.9 mg/cc, the metal, this Metallic microlattice is the world's lightest material. The scientists were able to make a material that consists of 99.99% air by designing the 0.01% solid at the nanometre, micron and millimetre scales.

How it was made? (leave this part if you couldnt understand, even i also couldnt... :))
     The research team first made a polymer microlattice template by exploiting an optical trick for growing polymer fibers using light. The process passes ultraviolet (UV) light through a perforated mask into a reservoir of resin that gets cured when it's exposed to UV. The resin traps light as it cures under each hole in the mask and forms a polymer fiber along the path of the light. Playing multiple light beams over the mask makes the fibers interconnect to form a lattice. The remaining uncured resin is washed out, the polymer template is coated in a thin layer of nickel, and the polymer is dissolved with lye, also known as sodium hydroxide. This leaves a "very thin" hollow lattice surrounding the original template.

What are its uses?
Uses for ultra light cellular materials include thermal insulation, battery electrodes and damping for acoustic, vibration and shock energy.