Material selection is one of the most consequential decisions in a 3D printing project — and one of the most commonly made by guessing. The right material depends on the part's mechanical requirements, temperature exposure, finish needs, and budget. This guide covers every major material across FDM, SLA, SLS, and metal printing with the practical properties you need to choose correctly.
Master Comparison Table
| Material | Process | Tensile Strength | Max Temp | Cost (bureau) | Best For |
|---|---|---|---|---|---|
| PLA | FDM | ~50 MPa | 50–60°C | $ | Prototypes, display models |
| PETG | FDM | ~50 MPa | 70–80°C | $ | Functional parts, enclosures |
| ASA | FDM | ~55 MPa | 90–100°C | $$ | Outdoor, UV-exposed parts |
| ABS | FDM | ~40 MPa | 80–105°C | $ | Machined prototypes, legacy |
| Nylon PA12 (FDM) | FDM | ~50 MPa | 100–110°C | $$ | Flexible functional parts |
| TPU / Flexible | FDM | ~25–40 MPa | 60–80°C | $$ | Gaskets, grips, phone cases |
| Polycarbonate (PC) | FDM | ~60 MPa | 110–130°C | $$ | Impact-resistant housings |
| CF-Nylon / Onyx | FDM | ~80–110 MPa | 105–115°C | $$$ | Structural, high stiffness |
| Standard Resin | SLA | ~40–65 MPa | 50–80°C | $$ | Display models, miniatures |
| ABS-like Resin | SLA | ~55–70 MPa | 60–80°C | $$ | Tough functional prototypes |
| Flexible Resin | SLA | ~5–8 MPa | 45–55°C | $$ | Soft-touch, compliant parts |
| Castable Resin | SLA | N/A | N/A | $$$ | Jewelry investment casting |
| Dental / Biocompat. | SLA | ~60–90 MPa | 70°C | $$$ | Medical devices, dental |
| Nylon PA12 (SLS) | SLS | ~50 MPa | 150–170°C | $$$ | Functional end-use parts |
| Nylon PA11 (SLS) | SLS | ~55 MPa | 150°C | $$$ | Impact, ductility critical |
| Glass-Filled Nylon | SLS | ~70 MPa | 175°C | $$$$ | Stiff, high-temp applications |
| Stainless 316L | DMLS | ~540 MPa | 800°C+ | $$$$$ | Corrosion-resistant metal parts |
| Titanium Ti6Al4V | DMLS | ~900–1100 MPa | 300°C+ | $$$$$ | Aerospace, medical implants |
| AlSi10Mg (Aluminum) | DMLS | ~400 MPa | 200°C | $$$$ | Lightweight structural parts |
| Inconel 718 | DMLS | ~980 MPa | 650°C | $$$$$ | High-temp, aerospace |
FDM Materials: The Full Breakdown
PLA — the default starting point
PLA is what most bureaus use for basic prototypes and display models. It prints cleanly, produces good surface quality, is cheap, and is easy to post-process (sand, paint, prime). Its main limitation is heat: PLA softens around 50–60°C, which means it can't be left in a hot car or used near heat sources. For anything that needs to actually function under load or temperature, PLA is a proof-of-concept material, not a final-production material.
PETG — the practical everyday choice
PETG is where most functional FDM work should start. It's stronger than PLA with better temperature resistance (70–80°C), handles mild chemical exposure without crazing, and is slightly flexible — which helps it absorb impact rather than crack. Layer adhesion is better than ABS without the warping issues. For enclosures, brackets, clips, and general mechanical parts, PETG is the right default if PLA isn't strong enough.
ASA — for anything that lives outside
ASA is the outdoor version of ABS. It's UV-stabilized, meaning it won't yellow or become brittle in sunlight the way standard PLA or ABS does. The mechanical properties are similar to ABS — decent impact resistance, temperature tolerance up to 90–100°C — but ASA holds those properties after months of weather exposure. Use it for enclosures, signage, brackets, and any part that will see direct sunlight.
Nylon (PA12, PA6) — flexible and fatigue-resistant
FDM nylon is the right choice for parts that need to flex repeatedly without breaking — living hinges, snap tabs, gear teeth. Nylon has better fatigue resistance than PETG and far better chemical resistance than most common FDM materials. The downside is moisture absorption: nylon is hygroscopic and must be dry-stored, and even then, surface finish on FDM nylon is typically rougher than PETG or PLA.
Polycarbonate (PC) — impact first, temperature second
PC is the material to reach for when impact resistance is the primary requirement. Clear PC is used for light pipes and lenses. Opaque PC handles aggressive mechanical abuse without cracking at the sharp stress concentrators where ABS or PETG would fail. Temperature resistance up to 110–130°C makes it suitable for applications near motors or electronics. PC is harder to print well than other materials — most bureaus run it on industrial-grade enclosed printers.
Carbon fiber composites — maximum stiffness
Carbon fiber filled nylon (Markforged Onyx, CF-Nylon, CF-PETG) combines the flexibility of nylon with dramatically higher stiffness. CF-Nylon is roughly 3x stiffer than standard PA12 at similar weight. The catch: CF composites are highly anisotropic. In-plane (XY) stiffness is excellent; through-layer (Z) strength is weaker. Parts should be oriented so loads run in the XY plane. Bureau availability for CF materials is more limited than standard FDM materials — confirm before designing around them.
TPU / Flexible filaments
TPU (thermoplastic polyurethane) is the standard flexible FDM material. Shore hardness ranges from 85A (very soft, rubber-like) to 98A (barely flexible). It's used for gaskets, grips, phone cases, shoe soles, and any part that needs to compress and recover. Layer adhesion on TPU is excellent, and it resists oils and abrasion well. Minimum feature sizes are larger than rigid materials — fine details tend to merge or lose definition.
SLA / Resin Materials
Standard resin
Standard photopolymer resin produces the smoothest surface of any common 3D printing material, with layer lines below 0.05mm that are invisible to the naked eye. The tradeoff is brittleness — standard resin parts snap cleanly under impact rather than bending first. For display models, architectural pieces, dental models, and miniatures, the surface quality justifies the brittleness. For anything load-bearing, choose a tougher resin.
ABS-like / Tough resin
Tough resins add flexibility and impact resistance at the cost of some surface quality. They behave more like ABS or PP — they'll deform slightly before breaking rather than shattering. For functional housings, snap-fit connectors, and mechanical prototypes in resin, tough or ABS-like resins are the right choice. Formlabs Tough 2000 and comparable resins from Phrozen, Asiga, and others are widely available at professional bureaus.
Flexible resin
Flexible resins produce parts with soft-touch or rubbery properties similar to silicone. They're used for grips, cushioned surfaces, ear tips, and compliant mechanisms. Flexible resin has lower tear resistance than TPU — it's best for lightly loaded compliant parts rather than anything that will be repeatedly flexed.
Castable resin
Castable resin burns out cleanly in an investment casting flask with minimal ash residue, making it the standard for jewelry and small metal casting from a 3D-printed pattern. Surface quality is high enough that cast pieces require minimal finishing. This is a specialized material — not every bureau stocks it. If you need castable patterns, specifically look for bureaus that list jewelry or casting services.
Biocompatible and dental resins
ISO 10993-certified resins are used for medical device prototypes, surgical guides, dental splints, and custom oral appliances. These resins are formulated to be safe for skin and mucous membrane contact and are tested for cytotoxicity. Handling requires strict protocols — dedicated machines, certified post-processing. Bureau availability for medical-grade SLA has expanded considerably over the past few years, but you'll still need to specifically source a bureau with medical capabilities.
SLS Nylon Materials
PA12 — the standard SLS material
Nylon PA12 is the default for SLS and MJF printing. It produces isotropic parts — meaning strength is the same in all directions, unlike FDM which is weak at layer boundaries. PA12 has good chemical resistance, can handle temperatures up to 150–170°C, and produces parts with enough surface quality to use directly as end-use components without post-processing. The standard gray finish from MJF PA12 is used in production parts across automotive, consumer electronics, and medical device industries.
PA11 — better impact, slightly more flexible
PA11 is bio-based (derived from castor oil) and has higher elongation at break than PA12 — meaning it bends further before snapping. For applications where impact resistance or ductility is more important than stiffness, PA11 is the better choice. It's slightly less available than PA12 but stocked at most professional SLS bureaus.
Glass-filled nylon
Adding glass fiber to SLS nylon increases stiffness and temperature resistance significantly — heat deflection temperature rises from around 150°C to 175°C or higher. Glass-filled parts are stiffer but more brittle than unfilled nylon. For structural housings, heat shields, and components near hot surfaces, glass-filled SLS nylon can replace machined engineering plastic in many applications.
Metal 3D Printing Materials
Stainless steel 316L
316L is the workhorse of metal 3D printing — austenitic stainless steel with excellent corrosion resistance, good weldability, and wide familiarity in engineering. It's used for food-contact parts, marine components, medical instruments, and chemical-resistant housings. As-printed 316L has tensile strength around 540 MPa. Hot isostatic pressing (HIP) can raise that above 600 MPa with better fatigue life.
Titanium Ti6Al4V
Titanium is the material of choice for aerospace and medical implants — high strength, low density (about half the weight of steel at similar strength), biocompatible, and corrosion-resistant. Ti6Al4V (Grade 5) is the most widely available titanium alloy in DMLS, with tensile strength around 900–1100 MPa depending on heat treatment. It's expensive per kilogram and slow to print — expect premium pricing and longer lead times versus stainless.
AlSi10Mg (aluminum alloy)
For lightweight structural parts where stainless steel is too heavy and titanium is too expensive, aluminum AlSi10Mg is the common middle ground. Tensile strength around 400 MPa with density roughly a third of steel. Heat treatment post-printing improves ductility and fatigue resistance. It's the go-to for automotive brackets, aerospace ducts, and heatsinks where weight savings matter.
Inconel 718
Inconel is a nickel superalloy built for extreme temperature applications — jet engine components, rocket nozzles, heat exchangers, industrial turbines. It retains mechanical properties at 650°C+ where most steels and aluminum would fail. Printing Inconel is slow and expensive, and machining it post-print requires carbide tooling. It's a specialized material for specialized applications — if you're not sure whether you need Inconel, you probably don't.
How to Choose the Right Material
Start with the function, not the material. Ask: What is this part doing? What temperature will it see? What loads? Does it need to flex? Does it need to look good? Does it contact skin or food? Once you've answered those questions, the material almost chooses itself — and if two materials could both work, the cheaper one usually wins.
Prototyping, no mechanical requirements: PLA (FDM) or Standard Resin (SLA). Fastest, cheapest, best surface quality for models and visual prototypes.
Functional parts, moderate loads, indoor use: PETG or Nylon PA12 FDM. PETG for simpler geometry; Nylon for parts that need to flex or fatigue well.
Outdoor exposure: ASA (FDM) or SLS PA12. ASA for low-cost outdoor parts; SLS for anything that needs to handle load reliably outdoors.
High detail, smooth surface, visual quality: SLA (any resin). Nothing matches resin for surface finish. Choose standard resin for display-only; tough resin for anything handled regularly.
Production parts, complex geometry, no support structures: SLS PA12 or HP MJF PA12. Isotropic properties, no support constraints, suitable for production quantities.
Metal properties required: DMLS/SLM in the appropriate alloy. Match alloy to environment: 316L for corrosion, Ti6Al4V for weight-critical or biocompatible, AlSi10Mg for lightweight structural, Inconel for high temperature.
Frequently Asked Questions
For static, lightly loaded indoor parts, PLA works fine. The problem is temperature — PLA softens at 50–60°C, which means a car interior in summer, a part near a motor, or a dishwasher can deform it. For anything that will be actively used and stressed, PETG is a better starting point with minimal cost difference at most bureaus.
Among commonly available materials: glass-filled SLS nylon (heat deflection ~175°C+) and polycarbonate FDM (110–130°C) are the top contenders for accessible printing. High-performance materials like PEEK and PEI (Ultem) handle 150–200°C but are expensive and require industrial-grade equipment. Most bureaus don't stock them routinely — confirm availability before designing around PEEK.
FDM parts are generally not food-safe — the layer lines trap bacteria and cleaning chemicals leach from filament. Some PETG filaments are technically food-safe but the printed part isn't because of surface porosity. For actual food contact, use SLS PA12 (which can be post-processed to food-grade surface) or 316L stainless steel from DMLS. Confirm food-grade certification with the bureau specifically — it's not automatic even with the right material.
Both use PA12 nylon as the base polymer, but the manufacturing process produces different properties. SLS nylon is isotropic — strength is equal in all three directions. FDM nylon is weak at layer boundaries (Z direction), sometimes 50–70% of XY strength. SLS also requires no support structures and can produce geometry that FDM cannot. The tradeoff is cost: SLS PA12 from a bureau costs 3–5x more per part than FDM PA12 for comparable sizes.
Resin (SLA) — specifically castable resin — is the standard for jewelry prototyping. The surface quality is far superior to FDM, details like prong tips and engraving reproduce cleanly, and castable resin burns out in an investment flask without ash residue. FDM is occasionally used for large statement pieces or costume jewelry where surface finish is less critical, but for anything that will be cast in precious metal, SLA castable resin is the correct process.
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