The perimeter construction

[1] (in English, contour crafting) is a construction printing technology, developed by Behrokh Khoshnevis") of the Information Sciences Institute at the University of Southern California (at the Viterbi School of Engineering)), which uses a mobile crane or computer-assisted gantry crane to construct buildings quickly and efficiently with considerably less manual labor. It was originally conceived as a method of building molds for industrial parts. Khoshnevis decided to adapt the technology for the construction of prefabricated homes as a method of reconstruction after a natural disaster, such as the devastating earthquakes that have devastated his native Iran.[2]​.

Using a quick-setting cement component, the perimeter construction forms the walls of the house layer by layer until they are finished with the floors and ceilings that are placed in place by the crane. The conceptual idea requires the embedding of structural components, plumbing, wiring, utilities and even consumer devices such as audiovisual systems as the layers are formed.[3]​.

The company Caterpillar Inc. provided funding to support the Viterbi project research in the summer of 2008.[4]​.

In 2009, Singularity University graduate students established the ACASA project with Khoshnevis as CTO to commercialize Contour Crafting.[5]​.

In 2010, Khoshnevis claimed that his system could build an entire house in a single day[6]​ and his electric-powered crane would produce very little construction material waste. In 2005, The Science Channel's Discoveries This Week reported that, given the amount of 3 to 7 tons of waste materials and exhaust gases produced by construction vehicles generated during conventional residential construction, perimeter construction was able to significantly reduce the environmental impact.

Khoshnevis stated in 2010 that NASA was evaluating perimeter construction for application in building bases on Mars and the Moon.[7] After three years, in 2013, NASA funded a small study at the University of Southern California to continue developing the Contour Crafting 3D printing technique. Potential applications of this technology include the construction of lunar structures with a material that could be made up of 90 percent lunar component with only 10 percent of the material brought from Earth.[8]​.

In 2017, Contour Crafting Corporation (of which Khoshnevis is CEO) announced a partnership and investment by Doka Ventures. In the press release, they maintain that "they will begin with the delivery of the first printers at the beginning of next year".[9]​.