3D Printing Materials: Filaments, Resins, Powders & Metals

3D printing materials are tied to the process that prints them, and that single fact shapes the whole selection. FDM extrudes a thermoplastic filament, SLA cures a liquid photopolymer resin, SLS and MJF fuse a polymer powder, and DMLS or SLM melts a metal powder. Each family runs only the materials built for its physics, and each carries its own balance of strength, temperature resistance, surface, and cost. The realistic first step in any material decision is to pick the process from what the part must do, then choose the material within that family.

This overview covers the four material families, the properties that drive selection, and a practical path to matching a material to an application. It follows the terminology of ISO/ASTM 52900, the public standard for additive manufacturing vocabulary, and the per-material pages carry the full property tables for each filament, resin, powder, and alloy.

How 3D printing materials are organized

The cleanest way to think about 3D printing materials is by the process family that runs them, because a material only works on the machine built for it. Filaments melt and extrude, so they serve FDM. Liquid resins cure under light, so they serve SLA. Polymer powders sinter or fuse under heat, so they serve SLS and MJF. Metal powders melt under a laser or electron beam, so they serve DMLS and SLM. Within each family the materials differ in strength, heat resistance, flexibility, and cost, but they all share the basic behavior of their process, including its accuracy and its characteristic weaknesses such as FDM anisotropy or the grainy as-built surface of the powder processes.

That shared behavior matters because it sets the ceiling on what a material can do in service. A nylon printed on FDM is not the same part as the same nylon printed on SLS, even if the chemistry is similar, because SLS fuses the powder in a way that produces a largely isotropic part while FDM lays it in tracks that are weaker across the layers. So when you compare materials, compare them within the process that will actually print them.

FDM filament materials

FDM offers the widest material range of any polymer process, from a few cents per gram for PLA to premium engineering grades. The common filaments cover a clear spread of properties, and the right choice depends on what the part must survive.

Easy-print commodity filaments

PLA is the easiest filament to print. It is stiff, dimensionally stable, and needs no heated enclosure, and it warps very little, which makes it the default for concept models and display parts. The trade-off is a low heat deflection temperature around 55 degrees Celsius and a brittle failure mode, so it does not suit hot or loaded service. PETG sits in the middle: it prints nearly as easily as PLA, with a heat deflection temperature near 70 degrees Celsius, and it is tougher and more ductile, which makes it a good general-purpose choice when PLA is too weak and ABS is too difficult.

Engineering and high-temperature filaments

ABS reaches a heat deflection temperature near 95 degrees Celsius and is tough and machinable, but it shrinks on cooling and needs a heated bed and a heated enclosure to print without warping. ASA behaves like ABS but adds UV resistance, which makes it the outdoor-grade choice for parts that see sun and weather. Nylon, in PA12 and PA6 grades, is strong and wear-resistant and works well for gears, bearings, and living hinges, but it is hygroscopic and must be stored dry. PA12 absorbs only about 1 percent moisture versus about 9 percent for PA6, which keeps it more dimensionally stable and is why PA12 dominates the powder processes; a wet nylon filament prints with steam, stringing, and weak layers.

TPU is a flexible filament sold across a Shore A 60 to 95 hardness range, good for gaskets, bumpers, seals, and overmolds. It prints slowly, benefits from a direct-drive extruder, and also needs dry storage because it absorbs moisture. At the top end of the filament range sit polycarbonate and ULTEM (PEI), which reach heat deflection temperatures above 200 degrees Celsius; these are printed only on specialized high-temperature machines with a heated chamber and a high-flow hotend.

Shared anisotropy

The shared weakness of every FDM material is anisotropy. Because each layer bonds to the one below as a warm bead, the bond between layers is weaker than the material within a track, and a printed part is typically 20 to 30 percent weaker along the Z, or build, direction than within the XY plane. That single fact drives most FDM design decisions: orient the part so functional loads run along the layers, never across them, and treat Z-axis strength as a design input.

SLA resin materials

Choosing a resin by application

SLA materials are photopolymer resins cured by a light source, and they are chosen by application rather than by a simple strength gradient. A standard resin gives the best surface and suits general prototypes and cosmetic parts. A tough, ABS-like resin is sturdier for functional prototypes that must take a knock or be assembled. A durable, polypropylene-like resin flexes and is used for living-hinge and snap-fit prototypes. A high-temperature resin reaches a heat deflection temperature of 200 to 280 degrees Celsius, which lets it serve as a mold insert for short-run injection molding or a high-heat fixture.

Specialty resins and shared traits

Flexible elastic resins span a Shore A 60 to 90 range and cover gaskets, grips, and overmold prototypes. Clear resins finish toward transparency for optical and display parts. Castable resins burn out cleanly and are used for investment casting patterns in jewelry and dental work. The shared trait across all SLA resins is that they are brittle thermosets that age under UV and heat, so they are weaker and less tough than engineering thermoplastics under impact, and a resin part left in sunlight will yellow and embrittle over time. SLA also wins on detail and surface, holding features down to about 0.2mm and an as-built finish that beats the powder processes.

SLS and MJF powder materials

PA12, PA11, and TPU powders

SLS and MJF run a nylon-centered material set, and the parts come out strong and largely isotropic, which is why these processes dominate functional work. PA12, nylon 12, is the primary material: strong, chemically resistant, and low in moisture uptake at about 1 percent, which keeps it dimensionally stable in humid service. PA11 is tougher and more ductile, with better elongation, which suits living hinges, snaps, and parts that must flex repeatedly. TPU powder prints flexible parts for gaskets, seals, and wearable components, with more consistent flexibility than FDM TPU because the powder bed supports the geometry.

Filled grades, surface, and supports

Glass-filled and carbon-filled nylons add stiffness and heat resistance for loaded and hot-service parts, at the cost of a rougher as-built surface and lower elongation. The filler trades toughness for rigidity, so a filled nylon is stiffer but snaps rather than bends past its limit. The shared trait of the powder processes is a slightly grainy, matte as-built surface that is commonly dyed, most often black, or smoothed in post-processing. MJF parts can be dyed in the build cycle, while SLS parts are typically dyed or vibratory-tumbled afterward. Neither process needs supports, which is a major advantage for parts with complex internal geometry or enclosed cavities that FDM or SLA could not reach.

Metal additive materials

Common alloys

Metal additive runs a small set of alloys chosen for how they fuse under a laser and how they perform in service. Aluminum AlSi10Mg is the light, weldable, general-purpose choice for lightweight structures, heat sinks, and housings where weight matters. Stainless 316L adds corrosion resistance for harsh and chemical environments, and is a common choice for marine, medical, and food-contact tooling. Titanium Ti-6Al-4V is the aerospace and medical choice, with a tensile strength of 895 to 1105 MPa and a density of 4.43 g/cm3, about 60 percent of steel, which gives an exceptional strength-to-weight ratio; it machines slowly because of its low thermal conductivity, so additive geometry that nears final form is attractive.

Cost and qualification context

Metal additive is an advanced, high-cost process. The parts come off the machine with residual stress, so they need stress relief heat treatment, support removal, and machining of critical faces, and the powder itself is a controlled, expensive consumable. It is reserved for complex geometry that earns its cost, such as internal cooling channels, topology-optimized brackets, or parts that machining cannot reach. No specific in-house capability is implied here; metal additive is treated as a specialty process to be sourced and qualified per project.

Choosing a material by application

By concept model, functional part, or detail

The shortest path to a material choice is to start from what the part must do, not from a material you like. For a concept model or display part that carries no load, PLA on FDM is the low-cost default. For a general functional prototype or housing that must take some load and run at room temperature, ABS, ASA, or PETG on FDM covers most needs. For a tough, repeatable functional part, especially one with snaps, living hinges, or complex internal geometry, SLS or MJF nylon in PA12 or PA11 is the better choice because it is isotropic and needs no supports.

By detail, metal, or heat

For the finest detail or a cosmetic, transparent, or tight-tolerance part, SLA with the right resin grade wins. For a metal part with complex geometry that machining cannot reach, metal additive in the right alloy is the answer, with the cost and lead-time implications that implies. For a part that must survive heat, match the heat deflection temperature to the service temperature: PLA fails above about 55 degrees Celsius, PETG around 70 degrees, nylon around 70 to 95 degrees depending on grade, ABS around 95 degrees, a high-temperature resin up to 280 degrees, and PEEK or Ultem above 200 degrees on specialized machines.

By flexibility or load

For a flexible part, pick TPU by hardness on FDM, or TPU powder on SLS or MJF for consistency and support-free geometry. For a loaded part, prefer SLS or MJF nylon or metal additive over FDM, and if FDM is the only option, respect its anisotropy by orienting the load along the layers and thickening the section to compensate.

Material properties that matter

Strength, heat, and moisture

A handful of properties drive most material decisions, and understanding them makes the choice faster. Tensile strength sets how much load a material carries, but in 3D printing the as-printed strength also depends on orientation, especially for FDM where the Z direction is 20 to 30 percent weaker. Heat deflection temperature (HDT) sets the upper service temperature before the material softens and creeps. Moisture absorption sets dimensional stability in humid service, which is why PA12 is preferred over PA6 for stable parts and why nylon and TPU need dry storage.

Impact, surface, and cost

Impact resistance sets toughness under a knock, where ABS, ASA, and nylon beat the brittle PLA and the cured SLA resins. Elongation at break sets ductility, where TPU and the durable resins stretch and where PLA and filled nylons snap. Surface finish and detail set the cosmetic quality, where SLA leads and where the powder processes leave a grainy matte. And cost sets the practical floor: FDM filaments are lowest, SLA resins are mid-range, SLS and MJF nylon cost more per part but remove support-removal labor, and metal powders are highest, driven by powder cost and the post-processing the parts need.

Special and advanced materials

Beyond the common families, a few specialty materials extend the range. Carbon-fiber-filled filaments, built on nylon, PETG, or ABS, roughly double stiffness and improve heat resistance, but the abrasive filler wears a standard brass nozzle quickly and calls for a hardened steel or ruby nozzle. Glass-filled nylons add stiffness and heat resistance on SLS and MJF. At the high end, PEEK and PEI (Ultem) reach heat deflection temperatures of 210 to 260 degrees Celsius and serve aerospace, medical, and oil-and-gas applications, but they are high-cost, high-difficulty materials that need specialized machines, and they require thorough drying before printing. These advanced polymers are flagged as high-risk for any capability claim and need confirmation against the actual operation.

Checklist

• Pick the process by accuracy, finish, and strength needs first, then the material within it.
• Match the material to the load, temperature, and environment of the part.
• Account for FDM anisotropy by orienting loads along the layers.
• For functional parts, prefer SLS or MJF nylon, or metal additive, over FDM.
• Allow for post-processing: support removal, dyeing, or machining of critical faces.
• Treat any food-safe, biocompatible, or regulated requirement as a material-qualification step that needs supplier confirmation.

Design rules

• Match the material to the load and environment: PLA for concept models, ABS, ASA, or PETG for general functional parts, nylon or PA12 for durable mechanical parts, and high-temperature resins or ULTEM for heat.
• Respect the process limits: FDM minimum walls near 0.8mm, SLA near 0.2mm, SLS near 0.8mm, MJF near 0.3mm in XY, and metal additive near 1.0mm supported.
• Store hygroscopic filaments and powders dry: nylon, TPU, and PETG absorb moisture and degrade if printed wet.

Tolerances

• Material properties are anisotropic in FDM, about 20 to 30 percent weaker across the layers, and more isotropic in SLS, MJF, and metal additive. Functional parts should account for build orientation, and critical faces in any process may need post-machining for a true fit. FDM tolerance is material-specific, typically about plus or minus 0.1 to 0.5mm, while SLS and MJF hold about plus or minus 0.3mm and metal additive about 0.3 percent of the part dimension with a 0.3mm floor.