When a functional 3D-printed part fails, the post-mortem usually points to the same culprit. It is rarely the printer, and it is rarely the design. Most of the time, the wrong material was chosen for the job. Because filament names get thrown around as if they were interchangeable, it is worth understanding what each common material actually does well — and where it lets you down.
Start with the job, not the material
Before comparing datasheets, describe the part’s working life in plain terms. Will it carry a sustained load or take impacts? Will it sit in a hot vehicle, near machinery, or outdoors in the sun? Will it touch solvents, oils or cleaning chemicals? Does it need to flex, or must it stay rigid? Honest answers to those questions narrow the field quickly, and they are exactly what a print bureau will ask when quoting your job.
PLA: accurate and stiff, but not a workhorse
PLA prints cleanly, holds dimensions well and costs the least, which is why it dominates visual models and form-fit checks. Its weaknesses matter for functional use: it is brittle under impact and begins softening at around 55–60°C, which is comfortably reached inside a parked car in an Australian summer. Indoor jigs, templates, organisers and low-stress fixtures are fine in PLA. Anything that lives in heat or takes knocks is not.
PETG: the sensible default for everyday parts
PETG trades a little of PLA’s crispness for meaningfully better toughness, chemical resistance and temperature tolerance (roughly 75°C before it softens). It has a slight give that helps it absorb impacts rather than shatter. Brackets, enclosures, guards, funnels and general-purpose workshop parts usually land here. If you are unsure what to specify, PETG is the safest starting point for a functional prototype.
ABS and ASA: heat and the outdoors
ABS is the classic engineering filament: good impact strength and a softening point near 100°C, suitable for parts that live around motors, electronics or vehicle interiors. Its sibling ASA adds genuine UV stability, making it the pick for anything permanently outdoors — mounts, housings and signage components that would chalk and crack in lesser materials. Both are prone to warping during printing, which is one of the better arguments for sending these jobs to a bureau with enclosed machines rather than fighting them on a desktop printer.
Nylon: wear surfaces and moving parts
For gears, bushes, hinges, clips and anything that slides or flexes repeatedly, nylon is hard to beat. It combines strength with abrasion resistance and a natural slipperiness that suits moving assemblies. The catch is that it absorbs moisture aggressively, which complicates both printing and long-term dimensional stability. Nylon parts are often best produced on SLS machines, where the powder process delivers consistent, isotropic strength without support marks.
TPU: when the part must bend
TPU is a flexible polyurethane used for gaskets, seals, grips, protective bumpers, vibration mounts and strain reliefs. It is specified by shore hardness — lower numbers are softer and rubbery, higher numbers approach the feel of a shopping trolley wheel. Flexible prints are slow and fiddly, so expect them to cost more per gram than rigid parts, but for the right application nothing else will do.
Why these plastics behave so differently
All of these materials are long chains of carbon-based molecules, and their real-world behaviour — stiffness, flexibility, softening temperature — comes down to how those chains are built and how they slide past one another as temperature rises. If you enjoy the science underneath the engineering, the team at Talking Science has an accessible explainer on why carbon chemistry makes materials like these possible.
When in doubt, describe the job
You do not need to arrive at a print bureau with a material already chosen. In fact, it is often better not to. Describe what the part must survive — loads, temperatures, chemicals, sunlight, flex cycles — and let the bureau match a material and a process to it. A five-minute conversation before printing is far cheaper than a failed part after it. If you have a job in mind, send through the model and the working conditions, and we will recommend the right material for it.
Our instant quote currently covers PLA, flexible TPU and resin; see TPU 3D printing for flexible parts. If PLA suits your part, see prototypes and functional parts or 3D printed replacement parts for how to order it.