Stereolithography was the beginning of the rapid prototyping industry and is still the most widely used. An SLA machine will build a part layer by layer, each layer being .002" to .006" thick, by using a solid-state laser beam to solidify the surface in a vat of liquid photopolymer, or SL resin.

The easiest 3D CAD file format Metro Rapid Prototyping can utilize is surface files (.STL) or any native ProE part file. IGS files can also be manipulated as well.

SLA models can be produced at Metro RP in a matter of hours or days, depending on the part size. The advantage using SLA prototypes over permanent hard tooling is the factor of time and cost. Prototype aluminum injection molds can take several weeks to produce and are several times the cost and lead time.

Some of the cleanest and most accurate prototypes come from SLA models using 3D CAD files. SLS machines are very quick and require little cleaning of the part off the machine, but the surface finish lacks the smoothness and detail as an SLA model. Typically, these parts are cheaper but require 2-3 times the amount of time to build.