3D printing materials: which one your part needs

The chooser

The five materials compared

PLA

The default. Plant-based, easy to print, sharp detail, many colours. Prusa's guide says it "gets soft and deforms at temperatures over 60 °C", degrades in UV light and tends to break along its layers on impact. Perfect for models, figures and prototypes; wrong for a car dashboard in January.

PETG

A cousin of the PET in drink bottles. Tougher and less brittle than PLA, with better layer adhesion, so it suits clips, holders and mechanical parts. One Australian service puts its heat limit at about 80 °C. It strings more while printing and scuffs more easily. Compared in detail: PLA vs PETG.

ABS and ASA

The engineering pair. ABS is tough, takes more heat and can be smoothed glossy with acetone, but it warps, gives off fumes and needs an enclosed printer; outdoors it yellows and turns brittle. ASA is its outdoor successor: Prusa rates it for UV and temperatures up to 93 °C, which makes it the pick for car parts and garden fittings. See PETG vs ABS.

TPU

A flexible, rubbery material for seals, bumpers, grips, feet and phone cases. Slower and fussier to print than the others, and the grade (how soft) varies a lot.

Resin

Resin printers cure liquid resin with light, layer by layer, for far finer detail than filament: the choice for miniatures and jewellery masters. Standard resins are more brittle than filament plastics, and uncured resin needs gloves and ventilation.

Nylon and filled engineering materials

Beyond the five everyday materials, engineering filaments cover parts that must be stiffer, stronger or more heat resistant. Nylon is tough, slightly flexible and wears well, which suits gears, hinges and parts that rub, but it absorbs moisture from the air and must be dried before printing. Polycarbonate (PC) takes high temperatures and impacts but needs a hot, enclosed printer. Carbon-fibre and glass-fibre filled blends of nylon, PETG or PLA are stiffer and more dimensionally stable than the base plastic, though the fibres are abrasive and need a hardened nozzle. These materials cost more per kilogram and are slower to dial in, so most hobby printers stick to the everyday five and a service prints the rest.

Special-effect filaments

Wood-filled, metal-filled, marble-look, glow-in-the-dark, silk and multi-colour filaments are mostly PLA with something added for looks. They are great for decorative pieces, gifts and models, but they are usually weaker or more brittle than plain PLA, and metal-filled and glow filaments can wear a brass nozzle. Choose them for appearance, never for a part that has to carry load.

Choosing by where the part will live

• Indoors, on a shelf: PLA. Cheap, sharp, any colour.
• In daily use, handled and dropped: PETG.
• Outdoors or in a car: ASA, which handles UV and heat; PETG is a second choice in shade.
• Near heat, such as a kitchen appliance or engine bay: ASA, ABS or PC, depending on the temperature.
• Flexing or gripping: TPU.
• Rubbing or sliding: nylon.
• Fine detail, small figures, jewellery masters: resin.

How strong a print is depends on more than the material

Two parts in the same plastic can differ hugely in strength. The number of outer walls (perimeters) matters more than infill for most parts; infill percentage and pattern matter for parts under compression; and layer orientation matters most of all, because prints are weakest between layers. A hook printed lying flat is far stronger than the same hook printed standing up. A good service will choose orientation and settings for the job, which is why it helps to tell them what the part has to do.

Keeping filament dry

Many filaments absorb moisture from the air, especially nylon, TPU, PETG and PC, and damp filament prints with bubbles, stringing and weak layers. Store spools in a sealed box with desiccant, and dry them in a filament dryer or a low oven setting suited to the material before printing if they have been left out. Melbourne's damp winters make this matter more than in drier cities.

Finishing a print

Layer lines are part of printed parts, but they can be reduced. Sanding and filler primer smooth PLA and PETG for painting; ABS can be smoothed with acetone vapour, which is why it is used for glossy parts; resin prints need washing and curing, then can be sanded and painted to a very fine finish. Finishing adds time and cost, so ask whether a part needs to look perfect or only work.

Safety

Printing PLA and PETG in a ventilated room is usually considered low risk, but ABS and ASA give off fumes and particles and should be printed in an enclosure with ventilation. Resin and its cleaning alcohol need gloves, eye protection and good ventilation, and uncured resin should never go down the sink. Keep printers away from flammable materials and do not leave a print running unattended for long periods unless the printer and room are set up for it.

Recycling and waste

PLA is often described as biodegradable, but in practice it only breaks down in industrial composting conditions, not in a home compost or landfill. Failed prints and supports are hard to recycle through kerbside bins. Reduce waste by printing a small test first, choosing settings that need fewer supports, and keeping offcuts for a filament recycler or a makerspace that collects them.

What materials cost

On cost, standard PLA and PETG are the cheapest filaments, ASA, ABS and TPU cost a little more, and engineering and filled materials cost noticeably more per kilogram. Resin is priced by the litre and usually costs more per part than PLA for anything but small detailed pieces. Our 3D printing cost guide shows how material, machine time and minimum charges add up for a real part.

Material choices for common jobs

Replacement parts for appliances. A clip, knob or bracket inside an appliance often sits near heat and takes repeated force. PETG is a good start; ASA or ABS if it sits near a heating element or motor. Check the original part for a material code moulded into it, such as PP, ABS or PA (nylon), and match it where you can.

Car interior parts. Australian car interiors get very hot in summer sun, well above the softening point of PLA. Use ASA for anything on or near the dashboard, and avoid PLA entirely in a car.

Garden and outdoor fittings. UV light breaks down PLA and ABS over time. ASA handles sun best; PETG is reasonable for parts in shade.

Toys and gifts. PLA prints cleanly in bright colours and is the easiest choice for display pieces and gifts. For toys that will be thrown, dropped or chewed, PETG is tougher, and nothing small enough to swallow should go to young children.

Prototypes. PLA is the cheapest way to check size, shape and fit. Once the design works, reprint in the material the final part needs.

Enclosures for electronics. PETG or ASA hold their shape better than PLA if the electronics get warm, and ASA suits enclosures that live outside.

Cosplay and props. PLA is easy to print and sand for painting; large helmets and armour pieces are often printed in sections and joined. TPU suits flexible straps and details.

How to tell what a part is made of

If you are replacing a broken plastic part, look for a recycling triangle or letters moulded into it: ABS, PC, PP, PA6 (nylon) or POM (acetal) are common in appliances. Polypropylene (PP) and acetal (POM) are hard to print well at home, so a printed replacement is usually made from PETG, nylon or ASA instead, designed with slightly thicker walls to make up the difference.

Colour and translucency

Colour affects more than looks. Dark filaments absorb more heat in the sun, which matters for parts in a car or outdoors. Translucent and clear filaments show the internal infill pattern unless printed solid, and are rarely truly transparent. Some pigments make filament slightly weaker or more brittle, which is why plain colours from the same brand can behave differently.

A simple way to decide

Start with PLA. If the part will get hot, go to PETG, then ASA. If it must bend, use TPU. If it must slide or wear, use nylon. If it must show fine detail at small size, use resin. Only move to an engineering material when the everyday options cannot do the job.

Printing temperatures at a glance

Each material prints in its own temperature range, set out by the filament maker on the spool. PLA prints coolest and needs the least from the printer; PETG a little hotter; ABS, ASA and nylon hotter again, with a heated bed and ideally an enclosure to stop warping; polycarbonate hottest of the common materials. TPU prints at moderate temperatures but slowly. If a printer cannot reach a material's range, or has no enclosure, that material is better printed by a service. Always start from the maker's recommended settings for the exact filament you are using, because brands differ.

Mixing materials in one print

Printers with more than one nozzle or a multi-material feeder can combine materials in one part, such as a rigid PETG body with soft TPU grips, or soluble supports that dissolve in water to free complex shapes. These setups are more complex and costly, so for most jobs it is simpler to print separate parts and fit them together.

Buying filament

Buy from a brand with consistent diameter and good reviews from people printing the same material; cheap spools with uneven diameter cause under- and over-extrusion that no setting can fix. Check the spool label for the recommended temperatures and the diameter your printer takes, which is 1.75 mm for most current printers. Buy one spool of a new material first, print a test piece, and only then buy in bulk. Keep the label or note the brand and colour, so you can match it if you need to reprint a part later.

Common questions