SLA has the distinction of being the oldest of the 3D printing technologies, first invented by Chuck Hull in 1983.

SLA works by exposing a layer of photosensitive liquid resin to a UV-laser beam so that the resin hardens and becomes solid. Once the laser has swept a layer of resin in the desired pattern and it begins to harden, the model-building platform in the liquid tank of the printer steps down the thickness of a single layer, and the laser begins to form the next layer. Each layer is built on top of the preceding one.

Like the FDM 3D printer technology, objects with overhangs 3D printed with this type of 3D printer will require support structures. And after printing has completed, the object must be rinsed with a solvent. Sometimes it’s also baked in a UV oven to finish processing.

SLA creates smooth surfaced objects with extreme detail, and it’s increasingly popular in industries like jewelry and cosmetic dentistry for creating castable molds.

Continuous Liquid Interface Production (CLIP) could be the next big thing in SLA 3D printing. This 3D printing technology also uses resin and an ultraviolet beam. The difference lies in an oxygen-permeable membrane that lies below the resin, which makes the process much faster. The inventors claim they can create objects up to 100 times faster. The first CLIP 3D printers already are in a test phase.