In photopolymerization techniques, light sensitive liquid resins are solidified by light irradiation. Areas which are irradiated solidify almost instantly. Mostly UV-light between 365 and 410 nm is applied through a window from underneath.

Digital Light Processing (DLP) offers high power intensities and the possibility to irradiate the entire printing platform at the same time. This makes DLP especially efficient. By combining of DLP with special windows or vat technology, exceptional printing speeds with high accuracy can be reached. All printers using photopolymerization, produce green parts which have to be cleaned of excessive resin and then post cured to achieve the final mechanical properties.