Start with the part's job, not the printer
The first question is never which printer to use, but what the part must do: look good, bear load, bend, survive heat, or resist chemicals. The function points straight to a material family, and only then to a process that can print it.
Unlike CNC, where almost any solid stock is fair game, 3D printing is tied to specific feedstocks: liquid resin, polymer powder, or filament. Picking the wrong family means the part simply cannot perform, no matter how well it is printed, so material leads and machine follows.
SLA resin: fine detail and smooth surface
Stereolithography cures a UV laser through liquid photopolymer, layer by layer, producing the finest features and smoothest surfaces of any desktop or industrial process. Standard resins capture sharp edges, thin walls, and textured masters that other methods blur.
The catch is brittleness: most resins are stiff but snap under impact and creep under sustained load, and they yellow outdoors. Use SLA for visual models, presentation pieces, casting patterns, and micro-fluidic or dental masters where appearance and accuracy dominate over mechanical duty.
SLS nylon: functional strength without supports
Selective laser sintering fuses nylon powder with a laser, and the surrounding unfused powder supports the part, so no manual supports are needed. PA12 nylon emerges strong, slightly flexible, chemically resistant, and ready for snap fits, enclosures, and end-use brackets.
Because the powder bed holds overhangs, SLS unlocks complex geometries, living hinges, and thin-walled ducting that would need supports elsewhere. Filled nylons add glass or aluminum for extra stiffness or heat deflection, making SLS the workhorse for functional prototypes and low-volume production.
FFF filament plastics: ABS, PLA, PETG
Fused filament fabrication, also called FDM, melts and lays down thermoplastic strand by strand. PLA is the easy, low-cost entry for visual models; ABS adds toughness and heat resistance; PETG balances strength, chemical resistance, and printability for functional parts.
FFF is the most accessible and cheapest process, but layer lines are visible and accuracy is the loosest of the three families. It suits large, low-detail enclosures, jigs, and proof-of-concept models where surface finish is secondary to cost and speed.
TPU and flexible materials
Thermoplastic polyurethane prints rubber-like parts that bend, stretch, and absorb impact without cracking. Shore hardness ranges from soft gel to semi-rigid, letting designers tune grip, cushioning, and seal behavior in the printed object itself.
Use TPU for phone cases, gaskets, vibration dampers, wearable straps, and soft-touch grips where a rigid plastic would fail. It prints on FFF machines with patience, or as a specialty filament, and holds up far better to repeated flexing than a rigid resin would.
PEEK and high-temperature polymers
At the top of the polymer range sit PEEK, PEKK, and ULTEM, which withstand continuous temperatures above 200 C, resist aggressive chemicals, and meet aerospace and medical approvals. They replace metal in weight-critical, heat-critical applications.
These materials demand high-chamber, tightly controlled printers and command a premium price, so they are reserved for true high-performance needs such as semiconductor tooling, aerospace brackets, and sterilizable medical devices rather than ordinary prototypes.
Reading the property sheet: mechanical, thermal, chemical
Every material publishes numbers that decide fit: tensile and flexural strength, elongation at break, glass-transition and melting temperature, and chemical resistance. A brittle high-detail resin and a tough nylon differ by an order of magnitude in impact strength.
Always match the number to the duty. A part that sits on a desk needs only stiffness and looks; a clip that snaps daily needs high elongation and fatigue resistance; a cook-adjacent bracket needs a high heat-deflection temperature. Let the load case pick the polymer.
Supports, design freedom, and anisotropy
Process choice changes how freely you can design. SLA and FFF need support structures for overhangs, which leave marks and eat time; SLS is support-free, so enclosed voids and interlocking parts print cleanly. This is why SLS wins complex functional geometry.
All printed plastics are somewhat anisotropic: strength is highest in-plane and lower across layers. Orient the part so the weakest direction does not align with the main load, and for FFF keep wall counts and infill high where stiffness matters.
Post-processing and surface finishing
Raw prints rarely ship as-is. SLA needs support removal and a UV cure, then can be sanded, primed, and painted to a high gloss; SLS parts are bead-blasted to remove loose powder and dyed or smoothed for a cleaner look.
FFF shows layer lines that require sanding or vapor smoothing; TPU is usually left as-printed. Budget finishing time into the quote, because a cheap raw print can become expensive once labor is added to reach a presentable surface.
Cost, lead time, and volume trade-offs
Material price and process speed set the economics. FFF is cheapest for a quick one-off; SLA adds detail at modest cost; SLS carries higher machine and powder cost but packs many parts in one bed, so per-part price drops fast at volume.
For a single prototype, pick the material closest to the final duty and the cheapest process that achieves it. For tens to hundreds of identical functional parts, SLS nylon often becomes the lowest total cost once support labor and scrap are counted.
A selection checklist and FabProto's material advice
Filter by function: looks and fine detail point to SLA resin; functional strength and complex shape point to SLS nylon; low cost and large parts point to FFF; flexibility points to TPU; heat or chemical duty points to PEEK or ULTEM. Match the polymer to the load, not the hype.
FabProto runs SLA, SLS, and FFF under one roof and stocks the common resins, nylons, and TPU grades. Send your model and tell us the operating condition; we recommend the right material and process, quote finishing, and print a prototype so you can feel the part before committing to volume.