What is SLS 3D Printing?

Last updated September 26, 2026

SLS (selective laser sintering) is a 3D printing process that builds parts from nylon powder. It produces stronger, more durable parts than resin printing, and it needs no support structures, which makes it a good fit for functional prototypes and low-volume end-use parts.

How it works

SLS is a powder bed fusion process:

  1. A thin layer of nylon powder is spread across a build chamber.
  2. A laser traces the cross-section of your part, heating the powder particles until they fuse (sinter) together.
  3. The build platform drops slightly, a fresh layer of powder is spread, and the laser sinters the next layer, bonding it to the one below.
  4. When the build finishes, the parts are buried in a block of unsintered powder. The powder is removed and recycled, and the parts are cleaned, usually by bead blasting.

Why no support structures matter

In most 3D printing processes, overhanging features need temporary supports that are printed with the part and removed afterward. In SLS, the loose powder surrounding the part supports it during the build. That has two practical benefits:

  • You can print complex geometries freely: interlocking parts, internal channels, lattices, and moving assemblies printed in one piece.
  • There are no support removal marks, so surface quality is consistent on all faces.

Material: nylon

SLS parts are printed from nylon powders, which give a good balance of strength, toughness, and chemical resistance. Nylon handles real mechanical load better than SLA resin and is far less brittle. Check the material dropdown in the quote editor for the current live list, and see 3D printing resins and nylons for a comparison.

Surface and tolerances

SLS parts have a slightly grainy, matte texture from the sintered powder, similar to a fine sugar cube. Layer lines are subtle but the surface is rougher than SLA. The default finish is “As Printed”; parts can be dyed or coated if you need color or a smoother feel. See As-machined vs. as-printed.

Tolerances are looser than CNC machining (±0.05mm standard). Like all printed processes, SLS parts can shrink slightly as they cool, so avoid designing precision mating features that depend on machined-level accuracy. See Tolerances explained.

When to use SLS

SLS is the right call when:

  • The part must function, not just look right: clips, brackets, hinges, ducts, and housings that take load or repeated handling.
  • The geometry is complex, with internal channels, lattices, or interlocking features that would need supports (or be impossible) in other processes.
  • You need small batches of end-use parts without paying for tooling, typically within the instant-quote range of 1 to 100 units.
  • You want a functional prototype in a durable plastic before committing to production.

SLS is not the right call when you need a smooth cosmetic surface (choose SLA), metal-level strength or heat resistance (choose CNC or metal 3D printing), or very tight tolerances.

For a full side-by-side of every process on the platform, see Choosing a process.