3D printing can be referred to as method of getting virtual 3D model printed onto a 2D object. 3D printing falls in the category of ‘rapid prototyping' technology. The function typically performed by 3D printers is that of printing consecutive layers on the previous ones for building up a 3D object. It is easier, more affordable, and faster to use 3D printers as compared to other technologies related to additive fabrication.

Technologies: Initially, production of a prototype required a lot of man-hours, tools, and experienced labor. For instance, after designing a novel Street Light Luminaire digitally, drawings used to be sent to accomplished craftsmen where the paper design used to be followed with utmost pains and a 3D prototype used to be formed in wood through the utilization of the entire shop that is full of costly tools and working machinery. One can easily make out that this process consumed a lot of time. Moreover, the skillful labor was not all that cheap. These shortcomings necessitated the need of rapid prototyping.

3D printing has a variation called Inkjet Printing System. It involves binding of fine powder layers (resins, cornstarch, or plaster) by the way of printing a gum from inkjet print head as per the shape of every cross-section as spotted by the CAD file. This is the only technology allowing full color prototypes to be printed. It is believed to be the quickest method.

Alternately, liquids are fed by these machines. Photopolymer is one of such kind. These machines make use of UV (ultraviolet) flood lamp. It is mounted in print head for curing each layer on its deposition. FDM (Fused deposition modeling) makes use of nozzle for depositing molten polymer layer by layer, on the support structure. The other approach is Selective Fusing of Print Media in the granular bed. Here, the media that has been unfused supports thin walls and overhangs in the piece which is being produced, thereby reducing need for temporary auxiliary supports for the work piece.

Ultimately, 3D Micro fabrication technique having a photo polymerization of 2-photons might be used to make ultra small features. Here, the preferred 3D object gets traced out by a completely focused laser in a gel block. The curing of gel into a solid takes place only in places where laser had been focused, owing to photo excitation's non-linear nature. The gel that is left out gets washed away.

Resolution: Resolution is measured in terms of layer thickness. The X-Y resolution is given in dpi. 100 microns is the characteristic layer thickness. The X-Y resolution is compatible with laser printers. Diameter of the particles, i.e. 3D dots is around 50-100 microns.

Applications: Standard applications are inclusive of design visualization, metal casting, CAD/prototyping, architecture, geospatial, education, healthcare, retail/entertainment, etc. Off late, 3D printing technology is being used in artistic expressions. Its biotechnological applications include bio-printing, computer-aided Tissue engineering, and organ printing.

Self-replication: The main purpose behind using 3D printing technology is its ability to replicate itself. RepRap is one such printer. It has the ability to print plastic parts and circuit boards. It is believed to print metals in future.