FDM and SLA are the two most popular 3D printing technologies, and choosing between them is the first decision on almost every project. Both can produce excellent parts, but they excel at different things. Here’s a practical comparison based on what we see across thousands of prints.

How Each Technology Works

FDM (Fused Deposition Modeling) melts a thermoplastic filament and lays it down layer by layer. It’s the workhorse of functional prototyping: fast, economical, and available in engineering materials like ABS, ASA, PETG, and carbon-fiber nylon.

SLA (Stereolithography) cures liquid resin with a laser, building parts with extremely fine layers. The result is smooth, detailed, and nearly injection-molding quality on the surface.

When FDM Is the Right Choice

Choose FDM when you need functional strength at low cost: enclosures, brackets, fixtures, and fit-check prototypes. It handles large parts economically, offers the widest range of durable thermoplastics, and turns around quickly. The trade-off is visible layer lines and less fine detail.

When SLA Is the Right Choice

Choose SLA when surface finish and detail matter most: presentation models, jewelry masters, dental and medical models, miniatures, and parts with fine features or text. SLA resins can also be castable, which is why jewelry designers rely on them for lost-wax casting workflows. The trade-offs are higher cost per part and resins that are generally more brittle than FDM thermoplastics.

Quick Comparison

Surface finish: SLA wins clearly. Strength and durability: FDM engineering filaments win. Fine detail: SLA. Large parts on a budget: FDM. Speed for simple parts: FDM. Castable or high-detail masters: SLA.

Still Not Sure? Ask an Engineer

Many projects actually use both: an SLA master for looks and an FDM version for function. At eCadCam in Los Angeles we run FDM, SLA, SLS, MJF, PolyJet, and DMLS metal in-house, so we’ll recommend the right technology for your part instead of forcing it into one process. Upload your file for an instant quote, or send us a sketch and we’ll take it from there.