3D Printing Materials: SLA Resin and SLS Nylon

Last updated September 26, 2026

OpusFab offers two polymer 3D printing processes, and each has its own material family. SLA printing uses liquid photopolymer resins cured by UV light; the standard option is Standard Resin. SLS printing fuses nylon powder with a laser; the standard option is PA12. Metal 3D printing is a separate process covered in Metal 3D Printing (DMLS/SLM).

SLA Standard Resin

Standard Resin produces the smoothest surface and finest detail of any polymer process on the platform. Layer lines are barely visible, and small features and embossed text come out crisp, so parts look close to injection molded.

Characteristics:

  • Excellent surface finish and fine detail
  • Rigid but brittle compared to thermoplastics: it snaps rather than bends
  • Properties can drift with long-term UV and moisture exposure
  • Standard tolerance shown at checkout: ±0.5mm
  • Default finish: As Printed

Typical uses: visual prototypes, fit-check models, presentation parts, and masters for molding, anywhere appearance matters more than mechanical load. See What is SLA 3D Printing?.

SLS PA12 nylon

PA12 is a nylon powder fused layer by layer. Because the unsintered powder supports the part during printing, SLS needs no support structures, which frees up geometry: internal channels, interlocking parts, and complex assemblies can print in one go.

Characteristics:

  • Durable and slightly flexible, with good impact and fatigue resistance
  • Near-isotropic strength, meaning similar properties in all directions
  • Handles heat better than SLA resin but softens above roughly 100°C
  • Slightly grainy, matte surface
  • Default finish: As Printed

Typical uses: functional prototypes, snap fits, living hinges, brackets, housings, and end-use parts in low volumes. See What is SLS 3D Printing?.

When printed materials beat machined ones

  • Complex geometry: internal channels, lattices, undercuts, and consolidated assemblies that no cutting tool can reach
  • One-off or very low quantity parts where machining setup dominates the cost
  • Speed for form and fit checks during development
  • Weight-saving structures that would waste most of a solid metal or plastic block

When machined materials beat printed ones

  • Tolerances: CNC holds ±0.05mm standard, while SLA resin is ±0.5mm
  • Material performance: machined metals and engineering plastics (including real POM and PEEK) outperform printed polymers in strength, heat resistance, and wear
  • Functional surfaces: a machined face beats any printed surface for sealing, bearing, or sliding contact
  • Larger parts and higher quantities, where per-unit machining cost drops below printing

Choosing between them

If the part is cosmetic or a quick fit check, SLA Standard Resin gives the best-looking result. If the part needs to work mechanically in low volumes, SLS PA12 is the practical printed option. If it carries real load, needs tight tolerances, or must survive heat and wear, machine it from metal or engineering plastic instead.

For a deeper design comparison, see CNC vs 3D Printing Design Rules and Choosing a Process.