Stereolithography (SLA or SL) is the method of additive manufacturing that focuses an ultraviolet (UV) laser onto a vat of photopolymer resin. A computer-guided laser draws one layer of a 3D model, called a slice. When introduced to UV light, the resin cures creating a solid layer of the 3D object. The support platform descends into the vat to allow the liquid resin to replace the hardened slice. This process repeats until the entire model is printed, from bottom to top. Afterward, the printed object is then post-cured in a UV oven before final finishing.


SLA was invented in the 1970s, but patents were not filed for the process until 1984 by Charles (Chuck) Hull. In 1986 he started his own company and coined the term 'Stereolithography'. This method is one of the most used in 3D printing, thanks to the techniques developed for SLA.

Printing & Finishing

New resin development have provided greater speed, strength, accuracy, and detail to the SLA process. SLA models can be used as stand-alone or form/fit/function pieces, fully detailed and finished. SLA is strong enough for machining, tapping, threading, and other secondary operations. Some uses include models for photos for brochures or catalogues and patterns for casting.

SLA parts are routinely polished, painted, and vacuum metallized, for convincing realism or structural integrity. Vacuum metallizing provides chrome, gold, or brass finishes. Copper/nickel plating enhances strength. Other metal finishes are also available upon request.

Learn more about these processes: Polish, Paint, and Metallize, 3D finishing for your prototypes.

SLA patterns are used in the casting process for urethanes (RTV molds), aluminum and zinc (sand casting or plaster casting), or as sacrificial 'Quickcast' patterns in the casting process. Casting metals is done by one of the several foundries with which APS has working relationships.

Turnaround Time

Turnaround time can vary due to size and complexity of parts. A small screw-like part may take an hour to build where as a 1:1 V8 engine may take a few days. APS is equipped for both. nearly any shape can be made, including shapes that would be impossible by any other manufacturing process.

Call with your questions or to request a quote, we look forward to hearing from you.