The index of refraction for a material tells you how much light will bend upon entering, and because all materials in Nature have an index of refraction greater than one, light will always bend in one direction, though to varying degrees. With metamaterials though, unnatural things happen thanks to indexes of refraction being less than one and even negative. Researchers at MIT have crafted a lens for radio waves with a negative index of reflection which allows it to focus the light down to a very precise point.
To build this lens the researchers used a unit cell they had previously designed as the building block. The inner structure was constructed using 3D printing and after the residue was washed away, a copper mist was used to plate the polymer, forming the unit cells in the larger structure. Importantly this is a relatively cheaper and easy way to produce a negative refraction lens. Also the lens itself is very light at less than a pound, which is a great improvement over the large, heavy, and expensive lens currently employed for focusing radio waves to a point.
Potentially this device could be used to study individual molecules by taking high-resolution images of them, or be installed in satellites for viewing the cosmos. However, it will likely leave its greatest impact in how it reshapes the field of metamaterials as other researchers use this fabrication method to create new metamaterial designs.