3D Printing Technologies Explained: FDM, SLA, SLS, MJF, and More
"3D printing" isn't one technology. It's eight different manufacturing processes that all build parts layer by layer but work in completely different ways, with different materials, costs, and applications.
Whether you're ordering parts from a service or choosing equipment for your shop, understanding what each technology actually does — and what it's good at — saves you from expensive mistakes.
FDM — Fused Deposition Modeling
How it works: A heated nozzle melts thermoplastic filament and deposits it layer by layer, building the part from bottom to top.
Materials: PLA, PETG, ABS, ASA, Nylon, TPU, Polycarbonate, Carbon Fiber composites, PEEK, ULTEM.
Best for: Prototypes, functional parts, jigs and fixtures, enclosures, large parts.
Limitations: Visible layer lines, limited detail on small features, support structures can leave marks.
Cost per part: $3-50 for typical parts. Cheapest technology for most applications.
Who uses it: Every 3D print shop. FDM is the workhorse — it handles 60-70% of typical shop volume.
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SLA — Stereolithography
How it works: A UV laser traces each layer's cross-section on liquid photopolymer resin, curing it solid. The build platform lifts and the next layer is cured on top.
Materials: Standard, tough, flexible, castable, dental/biocompatible, high-temperature, and engineering resins.
Best for: Visual prototypes, dental models and surgical guides, jewelry patterns, detailed miniatures, smooth surface finish parts.
Limitations: Parts are more brittle than FDM thermoplastics. Resins degrade in UV light. Post-processing required (wash + cure). Messy workflow.
Cost per part: $10-100 typically. Higher material cost and mandatory post-processing.
Who uses it: Dental labs, jewelry casters, product designers, anyone who needs smooth surfaces.
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SLS — Selective Laser Sintering
How it works: A laser fuses powdered material (usually Nylon PA 12) layer by layer. The unfused powder supports the part during printing, so no support structures are needed.
Materials: Nylon PA 12, Nylon PA 11, glass-filled nylon, TPU powder.
Best for: Functional end-use parts, small-batch production, complex geometries with internal channels, living hinges, snap fits.
Limitations: Grainy surface texture. Limited material selection. Machines are expensive ($100K-300K). Parts are always some shade of gray or white unless dyed.
Cost per part: $30-200 typically. The technology itself is expensive but per-part cost drops significantly in batches because the entire build volume can be packed with parts.
Who uses it: Production shops, engineering firms, aerospace and automotive suppliers.
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MJF — Multi Jet Fusion
How it works: HP's technology. An inkjet array deposits fusing and detailing agents onto a bed of nylon powder, then infrared energy fuses the patterned areas. Layer by layer.
Materials: Nylon PA 12, Nylon PA 11, TPU, and a growing list of HP-qualified powders.
Best for: Production parts, functional prototypes, medium-volume manufacturing. Similar applications to SLS but with faster throughput and more consistent mechanical properties.
Limitations: HP ecosystem lock-in (proprietary materials and machines). Parts come out gray — dyeing is common. Machines cost $300K+.
Cost per part: $25-150. Competitive with SLS, often cheaper at volume because MJF machines are faster.
Who uses it: Production bureaus, contract manufacturers, companies making hundreds to thousands of parts.
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Metal 3D Printing (DMLS / SLM)
How it works: A high-powered laser selectively melts fine metal powder layer by layer. The result is a fully dense metal part that can be heat-treated and machined like a traditionally manufactured component.
Materials: Stainless steel 316L, titanium Ti6Al4V, aluminum AlSi10Mg, Inconel 718, cobalt chrome, maraging steel, copper.
Best for: Aerospace components, medical implants, complex tooling with conformal cooling channels, parts that can't be machined or cast.
Limitations: Extremely expensive (machines cost $500K-1M+). Slow build rates. Parts typically need post-machining on critical surfaces. Support removal is difficult.
Cost per part: $100-1,000+ depending on size, material, and post-processing. Setup charges often $200-500 minimum.
Who uses it: Aerospace, medical, automotive, tooling specialists. Few general-purpose print shops have metal capability.
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DLP — Digital Light Processing
How it works: Similar to SLA but instead of a laser tracing each layer, an entire layer is projected at once using a digital light projector. Every pixel of the build area is cured simultaneously.
Materials: Same resin families as SLA — standard, tough, flexible, castable, dental.
Best for: Dental models (fast batch production), jewelry, any application where you're printing multiple small parts at once.
Limitations: Build area limited by projector resolution — larger builds sacrifice detail. Same resin handling as SLA (messy, requires wash and cure).
Cost per part: Similar to SLA. Faster for batches of small parts because the whole layer cures at once regardless of how many parts are on the build plate.
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PolyJet
How it works: Inkjet heads deposit tiny droplets of photopolymer resin, which are immediately UV-cured. Multiple materials can be jetted simultaneously from different heads.
Materials: Rigid, flexible, transparent, high-temperature, and biocompatible photopolymers. Multi-material and multi-color in a single print.
Best for: Multi-material prototypes, overmolded simulations (rigid body with rubber grip), full-color models, medical models for surgical planning.
Limitations: Expensive machines ($100K+) and materials. Parts are not as strong as FDM or SLS. Soluble support removal can be time-consuming.
Cost per part: $50-500+ depending on size. Premium pricing for premium capability.
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Binder Jetting
How it works: An inkjet head deposits a liquid binding agent onto a bed of powder (metal, sand, or ceramic). Layer by layer, the binder selectively glues the powder together. Metal binder-jet parts are then sintered in a furnace.
Materials: Stainless steel, tool steel, sand (for casting molds), ceramics, full-color sandstone.
Best for: Full-color architectural models, sand casting molds and cores, medium-volume metal parts (when sintered), decorative pieces.
Limitations: As-printed parts (before sintering) are fragile. Metal parts shrink ~20% during sintering and have lower density than DMLS. Limited structural applications without sintering.
Cost per part: $30-300 for sandstone/color models. Metal binder jetting is competitive with DMLS at higher volumes.
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