A 3D printer is a machine that creates a physical three-dimensional object from digital design data by adding material progressively rather than removing material from a larger block. This is known as additive manufacturing. A conventional 2D printer places material onto a flat sheet to create an image, whereas a 3D printer constructs an object with measurable height, width and depth.
The digital input is usually a three-dimensional model created with computer-aided design software or obtained from a three-dimensional scanning system. Software called a slicer converts that model into a sequence of machine instructions describing how the object should be constructed layer by layer. The printer then deposits, cures, sinters, melts or otherwise solidifies material according to those instructions. Common materials include thermoplastic filament, photopolymer resin, powdered polymers, metals and specialised composites. The technology is used for prototypes, educational models, replacement parts, tooling, artistic objects, research, manufacturing and numerous specialised applications.
There are several fundamentally different 3D-printing technologies. Fused deposition modelling, commonly abbreviated FDM, and the related term fused filament fabrication, or FFF, use a heated nozzle to extrude thermoplastic material layer by layer. Stereolithography, or SLA, uses light to selectively cure liquid photopolymer resin, while digital light processing uses projected light to cure larger portions of a resin layer. Selective laser sintering, or SLS, uses a laser to fuse powdered material, commonly polymer powder, into a solid structure.
Selective laser melting and related metal powder-bed fusion processes use high-energy sources to consolidate metal powders. Other systems use material jetting, binder jetting or specialised deposition methods. These technologies are not interchangeable: they differ in material behaviour, resolution, build speed, mechanical properties, surface finish, support requirements, operating costs and safety considerations. The broad term 3D printing therefore describes an entire family of additive manufacturing processes rather than one specific machine architecture.
A 3D printing workflow normally begins with a digital model. The model must have appropriate geometry for the intended printing process and should generally represent a closed volume where a solid object is required. The slicer analyses the geometry and divides it into horizontal layers or other manufacturing paths. It calculates perimeter or shell paths, internal infill, support structures, travel movements, material deposition parameters and other machine instructions.
In filament printing, for example, the slicer may specify nozzle temperature, extrusion rate, layer height, travel speed, cooling and infill density. The resulting instructions are sent to the printer through removable storage, USB, a network connection or a dedicated management system. The printer interprets these instructions using motors, heaters, sensors and controllers. The quality of the final object depends not only on the printer's nominal resolution but also on material behaviour, mechanical calibration, environmental conditions, layer adhesion, geometry and process parameters.
Layering is fundamental to most 3D printing. The machine creates a sequence of cross-sections that collectively approximate the desired three-dimensional geometry. Layer height affects vertical resolution, surface smoothness and printing time. Smaller layers can reduce visible stair-stepping on sloped surfaces but usually increase the number of layers and therefore the time required. Infill controls how much material is placed inside a nominally solid part, although the appropriate structure depends on the desired mechanical properties.
Perimeters or walls generally contribute substantially to strength and surface quality. Some geometries require support structures because the printer cannot deposit material reliably into empty space or maintain unsupported overhangs. Support material can be designed to break away, dissolve or be removed through other processes. Orientation is therefore an important design decision because it affects support requirements, surface quality, print time and the direction of mechanical strength.
Material selection strongly influences the properties of a printed object. Common FDM materials include PLA, ABS, PETG, nylon and various reinforced or modified polymers. PLA is relatively easy to print and is widely used for prototypes and educational work, while materials such as ABS and nylon have different thermal and mechanical characteristics. Resin printing can produce very fine detail but involves liquid photopolymers and additional washing and curing stages.
Metal additive manufacturing can produce strong functional parts but generally requires substantially more expensive equipment and controlled process conditions. Material behaviour can also produce anisotropy, meaning that a printed object's mechanical properties can vary depending on direction because the part was constructed layer by layer. Thermal contraction can cause warping or residual stress, especially with some high-temperature materials. Consequently, a 3D-printed part's strength cannot be inferred solely from its material name; geometry, print orientation, layer bonding, process parameters and post-processing also matter.
3D printing is valuable because it can manufacture complex geometries that would be difficult or expensive to produce using conventional subtractive or mould-based manufacturing. Designers can create internal channels, lattice structures, customised fittings and intricate prototypes without first producing specialised tooling. Rapid prototyping is one of the most established applications because a designer can modify a digital model and produce another physical version relatively quickly.
In medicine and healthcare research, additive manufacturing can support anatomical models, customised devices and certain specialised biomedical applications. In engineering, it can produce prototypes, jigs, fixtures and low-volume components. In education, students can turn digital designs into tangible objects and learn about geometry, engineering and manufacturing. In industrial production, additive manufacturing can be economical for customised or low-volume components, although conventional manufacturing methods remain more appropriate for many high-volume products.
The history of modern 3D printing is associated with additive manufacturing technologies developed during the 1980s. Stereolithography became one of the earliest commercially significant approaches, followed by technologies based on selective laser processing and extrusion. The term rapid prototyping became important because these systems allowed engineers to create physical representations of computer models without the lengthy tooling processes traditionally required. As patents expired, open-source hardware and software communities helped popularise desktop extrusion printers.
More recently, advances in resin systems, metal processing, automated manufacturing, multi-material systems and industrial process control have expanded the field. The distinction between hobbyist 3D printing and industrial additive manufacturing is increasingly important because industrial systems can use sophisticated materials, process monitoring and quality-control procedures that are very different from inexpensive desktop machines.
A 3D printer is not simply a more advanced paper printer. The output medium, materials, geometry, software pipeline and manufacturing process are fundamentally different. A 3D printer also does not necessarily produce objects that are immediately ready for their final use. Parts may require support removal, washing, curing, sanding, machining, heat treatment, painting or other post-processing. Dimensional accuracy can be affected by nozzle diameter, resin shrinkage, thermal expansion, machine calibration and other factors.
Safety requirements vary by technology and material; some processes involve heated surfaces, moving mechanisms, fumes, volatile chemicals, lasers or fine powders. Another misconception is that 3D printing can economically manufacture any object. Production economics depend on material cost, machine time, labour, post-processing, quality requirements and production volume. Its principal significance lies in providing digitally controlled additive manufacturing with a high degree of geometric flexibility and, in many contexts, rapid iteration or customisation.
