Additive Manufacturing also known as 3D Printing uses data from computer-aided-design (CAD) software that is converted to the most commonly used file type: Stereolithography files also known as STL to direct 3D printing hardware depositing material layer upon layer, in precise geometric shapes.
The process of additive manufacturing aids in rapid prototyping products for research and development companies the world over.
Additive Manufacturing has the added benefit of speed and cost over any other conventional means of manufacturing.
When real life functionality is required there is no better way to test fit prototypes before moving to mass production injection molding or cnc machining.