Additive manufacturing is a technique in which a three-dimensional object is produced by successively adding new layers of building material to those that have already been deposited. Recently, commercially available 3-D printers have been experiencing rapid development and so have 3-D-printing materials, including transparent media of high optical quality. These advancements open up new possibilities in many fields of science and technology including biology, medicine, metamaterials studies, robotics and micro-optics.
