3D Printer

A printer that is designed to create three-dimensional physical objects from a digital design using an additive process. 3D printers physically place thousands of horizontal wafer thin layers of material in locations specified by the program. These safe thin layers can be composed of plastic, resin or metal, depending on the type of printer being used. Initially design as a manufacturing technique, 3D printing can also be used to add coating onto a substrate, thus providing a highly customized localized deposition without expensive tooling. Problems that can occur with uneven surface finishes a potential structural defects. Additionally the printing process is extremely slow.

Note: 3D printing is a rapidly advancing field. As of 2026 there are multiple types of printing processes. Page links for each process provides additional info on the materials available for use.

The processes that use plastics are:

• Fused deposition modeling (FDM) 3D printers melt and extrude thermoplastic filaments, which a printer nozzle deposits layer by layer in the build area. FDM is also called Material Extrusion Printing and Fused Filament Fabrication (FFF). It has become popular for hobbyists because of the options for printer size and material selection.
• Stereolithography (SLA) 3D printers use a laser to cure thermosetting liquid resins into hardened plastic in a process called photopolymerization. This is the first 3D printing technology that was invented in the 1980s. SLA is also called vat polymerization and provides high resolution and accurate details.
• Selective laser sintering (SLS) 3D printers use a high-powered laser to fuse small particles of thermoplastic powder. These printers use a recoated to spread a thin layer off polymer powder, which is then letter using a laser. SLS is also called powder bed fusion. It typically uses nylon, glass-filled nylon, metal powders and ceramics.
• Polyjet printing use print heads to sprinkle tiny droplets of photopolymer resin onto a build plate, which then get hardened by a UV light in layers. Polyjet is capable of full-color and multi-material printing, but its materials are not known for their durability.
• Binder Jetting uses inkjet print heads to spray liquid binding agents onto a bed of powder, usually metal sand or ceramic. Binder jetting provides fast build speeds for mass production.

The processes that use metals (stainless steel, nickel alloys, aluminum, titanium, chromium) are:

• Metal FDM printers work similarly to traditional FDM printers, but use extruded metal rods held together by polymer binders. The finished “green” parts are then sintered in a furnace to remove the binder.
• Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) printers work similarly to SLS printers, but instead of fusing polymer powders, they fuse metal powder particles together layer by layer using a laser. SLM and DMLS 3D printers can create strong, accurate, and complex metal products, making this process ideal for aerospace, automotive, and medical applications.
• Electron beam melting (EBM) produces similar result to the laser melting of the metals. EBM does, however, require preheated vacuum environment for the construction process and this can result in coarser surfaces.
• Directed Energy Deposition (DED) uses a high-energy laser then deposits the molten metal via a nozzle. DED is fast with high deposition rates and the ability to cover large surfaces. However, fine detail is usually not possible. DED is primarily used for repairing and resurfacing expensive parts.

Resources and Citations

• Xometry: Types of 3D printing
• Formlabs: 3D Printers
• ProtoLabs: [1] Protolabs Manufacturing Accelerated]