Picking the right material.
Most printing disappointments are material choices, not printing failures. Here is how PETG, PLA and TPU actually behave once the part leaves the machine — written from printing all three daily rather than from a datasheet.
Three polymers, three jobs.
| Material | Best for | Strength | Heat tolerance | Watch out for |
|---|---|---|---|---|
| PETG | Functional and load-bearing parts, enclosures, outdoor use | High, with good toughness rather than brittleness | Good — comfortable well above typical indoor ambient | Can string; needs a dialled-in profile for clean surfaces |
| PLA | Form models, visual prototypes, fixtures used at room temperature | Stiff but brittle — snaps rather than bends | Poor — softens in a hot car or in direct sun | Do not use for anything structural that gets warm |
| TPU | Gaskets, seals, bumpers, grommets, strain reliefs | Flexible and highly abrasion resistant | Moderate | Prints slowly; sharp detail is harder to hold |
The default for parts that work.
If a part has a job beyond being looked at, PETG is usually the answer. It combines reasonable stiffness with genuine toughness, which is the property that matters most in practice: it deforms before it fails, instead of shattering without warning the way PLA does. That single behaviour makes it far more forgiving in enclosures, brackets, clips and anything that gets handled.
It also holds up better in real environments. Parts that live near warm electronics, in a vehicle, or outdoors survive in PETG where PLA would slowly sag. The trade-off is cosmetic — PETG is more prone to stringing and slightly less crisp on fine detail, so a display model may still look better in PLA.
- Use it for functional prototypes, housings, brackets, fixtures, anything load-bearing.
- Avoid it for parts where surface finish is the entire point.
Best looking, least durable.
PLA prints more accurately and more cleanly than anything else in this list. Sharp corners stay sharp, overhangs behave, and surfaces come out smooth with minimal fuss. For a model that has to be photographed or handed to a client, it is the right choice.
Its weakness is heat and brittleness. PLA begins to soften at temperatures a closed car in an Indian summer reaches comfortably, and it fails suddenly rather than gradually. A PLA bracket that has held for months can snap the first time it is shocked. Treat it as a communication material, not an engineering one.
- Use it for form and appearance models, concept reviews, low-stress fixtures indoors.
- Avoid it for anything structural, anything warm, anything outdoors.
When the part has to give.
TPU is a flexible thermoplastic that lets you print the rubbery parts of a product without commissioning a mould. Gaskets, sealing lips, vibration pads, cable strain reliefs and protective bumpers are all achievable, and the abrasion resistance is genuinely good.
The cost is time and precision. TPU prints slowly, and because the filament is soft it is less willing to hold very fine features. Design accordingly: generous radii, avoid thin unsupported spans, and expect a slightly softer edge than the CAD suggests.
- Use it for seals, gaskets, bumpers, grommets, flexible hinges.
- Avoid it for rigid structure or parts needing tight dimensional tolerance.
Common questions.
Which is stronger, PETG or PLA?
PLA is stiffer on paper, but PETG is tougher in use — it absorbs impact and deforms before breaking, while PLA is brittle and fails suddenly. For nearly every functional part, PETG is the stronger practical choice.
Can 3D printed parts be used outdoors?
PETG handles outdoor conditions considerably better than PLA, which softens with heat and degrades in sunlight. For prolonged outdoor exposure, material choice should be paired with design decisions like thicker walls and avoiding thin unsupported features.
Can you print a flexible gasket instead of moulding one?
Yes — TPU is well suited to gaskets, seals and bumpers, and it avoids committing to tooling while the design is still moving. For high volumes a moulded gasket is usually cheaper per unit, and that comparison is worth running before scaling.
Do you print materials beyond PETG, PLA and TPU?
Those three cover the overwhelming majority of jobs and are what we run in-house. Projects needing engineering polymers such as carbon-filled nylon are handled as part of a wider engineering engagement — send the requirement and we will tell you honestly whether it fits.
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