Additive printing (called 3D printing) - the process of producing three-dimensional physical objects based on a computer model. Initially, it was only one of the methods used for both rapid prototyping to build molds and prototypes themselves. With advances in accuracy of objects by a 3D printer, it also became a way of getting a ready-made objects.

File widely used as a standard in rapid prototyping methods. Most CAD software provides the option to save the output in STL format, which is a triangulation (triangular) representation of the geometry of surfaces in three-dimensional space.