3D Printing is the process of building three-dimensional physical objects from digital models by depositing material one thin layer at a time2. The category covers several distinct methods, including stereolithography (curing liquid resin with ultraviolet light), powder-bed printing with inkjet-style binder heads, and fused deposition of melted plastic filament2. Online, 3D printing grew its own subculture around file-sharing repositories where hobbyists trade printable designs, most visibly MakerBot's Thingiverse and Defense Distributed's DEFCAD4.

MIT's version of the process, called 3DP, spreads a thin layer of powder across a bed and uses inkjet-style print heads to selectively glue particles together into the desired shape2. Because different heads can dispense different binders or even different materials, that method can vary internal composition and surface texture within a single printed part2. The mix of open-source designs, cheap desktop kits, and free file libraries pulled 3D printing out of industrial labs and into garages, classrooms, and hackerspaces3.

Users typically start with a 3D model file (STL and OBJ formats are common), slice it into printer instructions using dedicated software, then send it to a printer that lays down molten plastic, cured resin, or bonded powder layer by layer2. Community sites like Thingiverse host free design files that anyone with a printer can download and print at home4, while services like Shapeways will print and ship parts for people who don't own a machine3. Enthusiasts often start with pre-made designs before moving on to CAD tools to build their own models, and hobbyist forums built around the RepRap ethic often push new users toward open-hardware kits rather than sealed consumer boxes3.