The material you print in matters as much as the technology you print with. An FDM part in PLA and an SLS part in nylon are both 3D printed, but they behave differently under load, tolerate temperature differently, and have different surface characteristics out of the machine. Choosing the right 3D printing material starts with understanding what the part actually needs to do — and which process and material combination delivers that.
Here’s a practical breakdown of the most common 3D printing materials organized by technology, with notes on where each works well and where it doesn’t.
FDM 3D Printing Materials: Workhorse Thermoplastics
FDM (Fused Deposition Modeling) builds parts by extruding melted thermoplastic filament layer by layer. The material range is wide, and the right choice depends on what the part needs to survive.
PLA is the most common FDM material — easy to print, dimensionally stable, and available in a wide range of colors. It’s well-suited for visual prototypes, concept models, and low-stress functional parts. The limitation is heat resistance: PLA begins to soften around 60°C, which rules it out for anything that will be near heat sources or left in a hot car.
ABS is tougher than PLA and handles higher temperatures (up to ~100°C), making it better for functional parts that need to survive real-world conditions. It’s also easier to post-process — ABS can be sanded and acetone-smoothed to a much better surface finish than PLA. The tradeoff is that ABS is more demanding to print: it requires a heated chamber or enclosure to prevent warping, and it off-gasses during printing.
PETG sits between PLA and ABS in most respects. It’s stronger and more temperature-resistant than PLA, easier to print than ABS, and reasonably impact-resistant. It’s a good default for functional prototypes that need to be durable without the printing complexity of ABS.
Engineering-grade filaments — including nylon, polycarbonate, PEEK, and carbon fiber-filled variants — push FDM into territory that competes with injection-molded engineering plastics. Polycarbonate handles temperatures above 100°C and is significantly stronger than ABS. PEEK is used in aerospace and medical applications where chemical resistance and high-temperature performance are required. These materials require high-temperature print heads and often enclosed, controlled environments to print reliably.
SLA Materials: Resins for Detail and Surface Quality
SLA (Stereolithography) cures liquid resin with a UV light source, producing parts with much finer feature detail and smoother surface finish than FDM. The tradeoff is that resin parts are generally more brittle than thermoplastics and require post-curing after printing.
Standard resins are well-suited for detailed visual models, master patterns for mold making, and parts where surface quality matters more than toughness. They produce excellent surface finish straight off the machine but are not impact-resistant and will crack under stress.
Tough and ABS-like resins improve on the brittleness of standard resins and are used for functional prototypes that need to survive assembly and light mechanical testing. They’re not as strong as actual ABS, but they’re significantly more durable than standard SLA resin.
Flexible and rubber-like resins produce parts with Shore hardness in the 40–80A range — useful for gaskets, grips, overmold simulations, and anything that needs to flex or compress. These aren’t elastomers in the engineering sense, but they approximate the behavior well enough for prototype and testing purposes.
Castable resins are designed to burn out cleanly in a casting furnace, making them the right material when SLA is being used to produce patterns for metal casting rather than end-use parts. This is relevant for jewelry, dental work, and small-batch metal part production.
SLS Materials: Functional Nylon for Production-Grade Parts
SLS (Selective Laser Sintering) fuses powdered nylon with a laser, producing parts without support structures — the surrounding unfused powder supports the build. The result is fully dense nylon parts with good mechanical properties, excellent chemical resistance, and surface characteristics that are suitable for functional testing and end-use applications.
Nylon 12 (PA12) is the most common SLS material. It’s strong, flexible enough to handle snap fits and living hinges, and resistant to chemicals and moisture. SLS nylon parts look and feel different from FDM or SLA parts — the surface has a characteristic matte, slightly granular texture. It can be dyed, painted, or coated, but it won’t have the smooth surface of an SLA part without post-processing.
Glass-filled nylon adds stiffness and improves temperature resistance at the cost of some impact toughness. Used where the standard nylon is too flexible or where the part needs to hold tighter dimensional tolerances under varying temperature.
TPU powder produces flexible, rubber-like SLS parts with better mechanical properties than flexible SLA resins — more tear-resistant, more consistent, and printable in complex geometries without support structures. Used for gaskets, flexible connectors, and impact-absorbing components.
Choosing the Right Material
The starting point is the part’s functional requirements: operating temperature, mechanical loads, chemical exposure, surface finish requirements, and whether the part is a prototype or intended for end use. From there, the printing technology narrows the material options, and the material selection drives the rest of the process decisions.
For a comparison of which 3D printing technology fits which applications, or specifically which technology is right for functional parts, those are covered separately. If you’re working through a material decision for a specific part, get in touch — we run FDM, SLA, and SLS in-house and can recommend the right combination for what you’re making. Call us at 718-557-9578.
