3D printers use additive manufacturing to build solid objects layer by layer using materials like powdered resin, metal, or paper. CAD software is used to design objects digitally and can then be 3D printed. There are different types of 3D printing including direct 3D printing which uses inkjet printing technology to deposit material layer by layer, and binder 3D printing which is similar but uses a binder to join dry powder layers. 3D printing enables the creation of complex geometries and customized parts for industries like aerospace, automotive, robotics, and more.