Stereolithography (SLA) was the first 3D printing process and is based on light curing (photopolymerization) of liquid materials into a solid shape.

In this process a vat of liquid resin is exposed to controlled lighting by a laser or a digital light projector, or DLP, which causes the resin to harden and cure. The build plate then moves down into the resin and the light cures resin layer by layer, as the bed moves up in small increments. The process repeats until the model has been built.

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Typically, SLA printers allow for higher resolutions to be printed, but there are limitations on the size of the build area. This makes SLA printers excellent for small parts with fine details, such as molds for jewelry. Generally, the resins used in SLA printers is a mixture of acrylates and photoinitiators (the chemical activated in the curing process). Companies, such as Form Labs, have created a variety of types of resins to allow the resulting material to have different properties.

Recently, the use of stereoligraphic 3D printing techniques has been developed further to allow for the additive manufacturing of ceramic and biocompatible materials. Successful 3D printing of ceramics using SLA requires firing of parts in a kiln after printing.