SLS vs SLA vs FDM: Which 3D Printing Process to Choose

June 28, 2026

SLS, SLA, and FDM are the three most common 3D printing processes: SLS fuses nylon powder with a laser for strong functional parts, SLA cures liquid resin for smooth, highly detailed parts, and FDM extrudes melted plastic filament for low-cost prototypes. The right choice depends on whether you need strength, detail, or low cost.

Key takeaways

SLS → strong, functional nylon parts, no supports, complex geometry and batches.
SLA → smoothest surface and finest detail; resin parts can be brittle.
FDM → cheapest and fastest for basic prototypes; visible layer lines, weaker along layers.
Choose by priority: strength → SLS, detail/finish → SLA, cost → FDM.

This guide compares the three processes so you can choose. For a deep dive on powder-bed printing, see our SLS 3D printing guide, or order parts with our 3D printing services.

SLS vs SLA vs FDM at a glance

Factor	SLS	SLA	FDM
How it works	Laser fuses nylon powder	Laser/light cures liquid resin	Extrudes melted filament
Materials	Nylon PA12/PA11	Photopolymer resins	PLA, ABS, PETG, nylon
Strength	High, isotropic	Moderate, can be brittle	Moderate, weak along layers
Accuracy & detail	Good	Excellent (finest)	Fair
Surface finish	Slightly grainy/matte	Very smooth	Visible layer lines
Supports	None (powder bed)	Required	Required
Cost	Medium	Medium	Lowest
Best for	Functional parts, batches	Detail, smooth cosmetic parts	Cheap, fast prototypes

SLS (Selective Laser Sintering)

SLS uses a laser to fuse nylon powder layer by layer. Because the surrounding powder supports the part, SLS prints complex geometries and overhangs with no support structures, and you can nest many parts in one build. Parts are strong and isotropic, making SLS the best choice for functional, end-use parts and small production runs. Read more in our SLS guide.

SLA (Stereolithography)

SLA cures liquid photopolymer resin with a laser or light source, producing the smoothest surfaces and finest detail of the three. It is ideal for cosmetic models, master patterns, and parts with fine features. The trade-off is that standard resins can be brittle and may degrade in UV over time.

FDM (Fused Deposition Modeling)

FDM extrudes melted thermoplastic filament (PLA, ABS, PETG) layer by layer. It is the cheapest and most accessible process, great for quick form-and-fit prototypes and jigs. Parts show visible layer lines and are weaker along the layer direction, so it is less suited to fine detail or high-strength end-use parts.

How to choose: SLS vs SLA vs FDM

Need strength and function? Choose SLS (nylon, no supports, isotropic).
Need fine detail or a smooth cosmetic finish? Choose SLA.
Need the lowest cost for a basic prototype? Choose FDM.
Need metal or a few hundred plastic parts? Consider metal 3D printing or urethane vacuum casting instead.

Frequently asked questions

Which is stronger, SLS, SLA, or FDM?

SLS is generally the strongest because its nylon parts are dense and isotropic. SLA strength depends on the resin and can be brittle, and FDM parts are weak along the layer lines.

Which 3D printing process has the best surface finish?

SLA produces the smoothest surface and finest detail. SLS is slightly grainy, and FDM shows visible layer lines.

Which is cheapest?

FDM is the lowest-cost and fastest process for basic prototypes. SLS and SLA cost more but deliver stronger or more detailed parts.

Which process is best for functional end-use parts?

SLS, because its support-free nylon parts are strong in all directions and handle complex geometry, making them suitable for end use and small batches.

Not sure which process fits your part? Upload your CAD to Sendot Technology and we will recommend SLS, SLA, FDM, or metal printing with a quote on 3D printing services. Request a quote.

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