The earliest 3D printers appeared in the 1980s. These machines used lasers to cure light-sensitive materials into specific designs. It was during this time that the slicing process first appeared and designers used computer programs to split 3D designs into a series of connected layers. The stereolithography machines used these layers as guides for their lasers, curing models one bit at a time.
Many modern 3D printers use the same style of slicing software that was used for the early machines. The most significant difference between the newest machines and the prototyping machines of the 1990s is the use of many different materials instead of just a light-cured polymer. Today’s extrusion process is called fused filament fabrication (FFF), which describes the way materials melt and extrude in modern 3D printing.
Direct metal laser sintering (DMLS) machines, use a process similar to the original stereolithography machines, except they sinter metal powder into solid forms. This process opened up many possibilities for companies that rely on machined metal parts. Unlike parts created with older CNC machines, DMLS industrial 3D printers could generate intricate structures on the inside of each piece.
Polyjet printers, also known as multi-jet printers (MJP), use several extruders to create robust designs with different colors and materials. These new forms of 3D printing are only available with industrial 3D printers right now, but the technology is rapidly evolving and consumer models may offer more robust print options in the future.