Stereolithography (SLA)

Stereolithography (SLA) 3D prints photopolymer resins with fine detail and smooth surfaces, ideal for high-accuracy prototypes, clear parts, and low-volume plastic components.

Overview

Stereolithography (SLA) uses a UV laser to cure liquid photopolymer resin layer by layer, producing highly detailed plastic parts with very smooth surfaces. It excels at small to medium-sized components that need tight features, sharp details, and cosmetic-quality finishes straight off the machine.

Use SLA for form/fit prototypes, clear or translucent parts, complex internal channels, and master patterns for molding or casting. It handles thin walls and fine text well and can produce functional parts in tough or high-temperature resins, but most materials are more brittle and less UV-stable than production thermoplastics. Dimensional accuracy is good, but parts can warp or shrink if you ignore wall thickness, orientation, and support strategy.

Tradeoffs: excellent resolution and surface finish, moderate strength, limited long-term durability, and part-size constraints. Best for low-volume runs and prototypes where appearance, precision, or optical clarity matter more than rugged, long-life performance.

Common Materials

  • Standard photopolymer resin
  • ABS-like photopolymer resin
  • Tough photopolymer resin
  • Clear photopolymer resin
  • High-temperature photopolymer resin

Tolerances

±0.002–0.005" on well-supported, properly oriented features

Applications

  • Form and fit prototypes
  • Small enclosures and housings
  • Clear lenses, light pipes, and optical mockups
  • Dental and medical models
  • Casting patterns and silicone mold masters
  • Microfluidic and complex internal-channel parts

When to Choose Stereolithography (SLA)

Choose SLA when you need very fine detail, sharp features, or cosmetic surfaces on plastic parts at low volumes. It is especially strong for clear parts, intricate internal geometries, and high-accuracy form/fit prototypes. Ideal for master patterns, appearance models, and functional prototypes where strength is moderate and long-term UV exposure is limited.

vs Fused Deposition Modeling (FDM)

Pick SLA over FDM when you need smoother surfaces, finer details, or small features that would be stepped or fragile in filament prints. SLA is better for clear parts, thin walls, and accurate small components where support scars and layer lines from FDM are unacceptable.

vs Selective Laser Sintering (SLS)

Pick SLA over SLS when surface finish, small feature resolution, or optical clarity matter more than mechanical robustness and powder handling. SLA is also preferred for master patterns and aesthetic prototypes where the rougher grain of SLS would require heavy post-processing.

vs Multi Jet Fusion (MJF)

Pick SLA over MJF for cosmetic prototypes, transparent parts, and very fine features that need minimal grain and high edge definition. SLA is better suited to low-volume, high-detail work where you can accept more brittle materials in exchange for crisp details and smooth surfaces.

vs Digital Light Processing (DLP)

Pick SLA over DLP for slightly larger parts where consistent accuracy over a bigger build area is more important than maximum print speed. SLA systems are often more forgiving on very fine, tall features due to their scanning laser exposure profile.

vs PolyJet

Pick SLA over PolyJet when you need highly detailed single-material parts with excellent surface finish at lower part cost. SLA is typically more economical for general-purpose prototypes and masters when you do not need multi-material or rubber-like regions in the same build.

Design Considerations

  • Maintain minimum wall thickness of ~0.5–0.8 mm for unsupported walls and increase thickness for larger, load-bearing features
  • Add drain and vent holes for hollow or trapped-volume geometries to allow resin removal and reduce suction forces during printing
  • Avoid large, flat, unsupported surfaces; break them up with ribs or slight curvature to reduce warpage and cupping
  • Design parts with support removal in mind by placing cosmetic surfaces away from expected support contact areas
  • Use generous fillets at wall intersections and base transitions to reduce stress concentrations and improve print success
  • Specify tolerances realistically and allow clearance on mating features, then plan to tune critical fits with light sanding or secondary machining if needed