How do 3D printers work?

RepRap 3D printer with inventor Adrian Bowyer (©SPL)

The overriding principle of 3D printing is that hundreds of layers about 0.1mm thick are stuck on top of each other by a machine to eventually produce a solid, 3D object from a computer model or a replica of the mould. In essence it works in much the same way as a traditional inkjet printer, where the ink is printed in layers to form a image. Instaed of ink, however ,a 3D printer uses molten plastic, thick waxes and other materials to create the desired object.

3D printers are capable of producing protypes from computer drawings, such as this NASA space plane (© NASA)

There are several different methods of 3D printing that can vary somewhat in application. A binder 3D printer uses a fine dry powder with liquid glue to form layers and ultimately a solid object. Another method, photopolymerisation, fuses liquid plastic with a beam of ultraviolet light that solidifies the liquid. Selective laser sintering, meanwhile, uses a laser to melt a plastic powder that solidifies to form a particular layer.