The Short Answer
If you're printing something indoors that doesn't get hot and doesn't need to flex, use PLA. If the part needs to handle stress, moisture, or mild heat, use PETG. If it's going outside or into a car, use ASA.
That covers 95% of decisions. The rest of this guide explains the reasoning behind that rule, the edge cases where it breaks, and the practical differences you'll actually notice when printing each material.
Quick Comparison Table
| Property | PLA | PETG | ASA |
|---|---|---|---|
| Print temperature | 190–220°C | 230–250°C | 240–260°C |
| Bed temperature | 50–60°C | 70–85°C | 90–110°C |
| Enclosure required | No | No | Yes (strongly recommended) |
| Heat resistance | Low (~60°C) | Moderate (~80°C) | High (~100°C) |
| UV resistance | Poor — yellows and embrittles | Moderate | Excellent |
| Impact resistance | Moderate — brittle under impact | Good — flexible under stress | Good |
| Water resistance | Absorbs moisture, degrades | Good | Good |
| Ease of printing | Very easy | Easy | Difficult — warps, needs enclosure |
| Stringing tendency | Low | High — needs careful retraction tuning | Moderate |
| Price (approx) | €12–18/kg | €13–20/kg | €18–28/kg |
| Best for | Prototypes, display, art, indoor functional | Mechanical parts, clips, brackets, anything that flexes | Outdoor parts, automotive, anything in the sun |
PLA — The Default
PLA (Polylactic Acid) is derived from corn starch or sugarcane, making it biodegradable under industrial composting conditions — though not in your garden or a landfill. It's the easiest filament to print, the most forgiving of settings errors, and the cheapest. For these reasons, it's the right default choice for most prints.
Print with PLA when: you're making display pieces, prototypes, decorative items, organizers, phone stands, figurines, or any functional part that will live indoors and not get hot. PLA handles the vast majority of everyday household prints perfectly.
PLA's weakness is heat. At around 60°C it begins to soften — which means a car dashboard in summer will deform your PLA mount, direct sunlight through a window can warp a PLA hook, and a PLA bracket near a radiator will slowly creep. This trips up a lot of beginners who print something that works fine indoors in winter, then watch it fail the next August.
The other limitation is brittleness. PLA is stiff and hard, which is great for dimensional accuracy, but it snaps rather than bends under impact. A PLA clip or snap-fit joint that gets repeatedly stressed will eventually crack along layer lines. For anything that needs to flex — cable clips, spring-loaded parts, living hinges — PETG is the right choice.
PLA variants like PLA+ and High-Speed PLA improve on these weaknesses somewhat. PLA+ typically has better layer adhesion and slightly more impact resistance. High-Speed PLA (marketed by Bambu Lab and others) is optimised for fast printing with less quality loss at speed. Neither changes the fundamental heat limitation.
If you're printing PLA and getting layer separation on functional parts, try increasing your nozzle temperature by 5°C. PLA at 200°C and PLA at 215°C can print identically on the surface but have meaningfully different layer bonding strength.
PETG — The Workhorse
PETG (Polyethylene Terephthalate Glycol) is the material that food and drink bottles are made from — the G (glycol) modification makes it less brittle than standard PET and easier to print. It sits between PLA and engineering materials in terms of difficulty and performance, which makes it the sweet spot for functional parts.
Print with PETG when: you need a part that flexes, takes impact, resists water, or operates in environments above 60°C. Cable management clips, snap-fits, brackets, tool holders, phone cases, and anything going near moisture are ideal PETG use cases.
PETG's main printing challenge is stringing. Because it's stickier than PLA, it tends to leave thin threads between features on complex models. Getting stringing under control requires dialling in retraction — typically 0.8–1.2mm on direct drive extruders, 4–6mm on Bowden. The other fix is reducing travel speed or enabling combing in your slicer so the nozzle avoids crossing gaps wherever possible.
The other thing to know about PETG is its layer adhesion — it bonds very well to itself, which is one reason it's so impact-resistant. But this also means it sticks aggressively to glass print beds. Use a separator like a glue stick or hairspray on glass, or switch to a PEI-coated plate where PETG releases cleanly after cooling.
PETG also absorbs moisture from the air. A wet spool will print with visible bubbles and rough surfaces. If you've had a PETG spool sitting open for a week, dry it at 65°C for 4–6 hours before printing. This matters more for PETG than PLA.
PETG scratches PEI surfaces if you remove parts before the bed fully cools. Always let PETG prints cool to below 40°C before removing — they release cleanly at room temperature and without force.
ASA — The Outdoor Material
ASA (Acrylonitrile Styrene Acrylate) was developed specifically as an outdoor-rated alternative to ABS. It has the same temperature and chemical resistance as ABS but with significantly better UV stability — it doesn't yellow or embrittle after months in the sun the way ABS does. If you're printing anything that will live outside, ASA is the right call.
Print with ASA when: the part will be exposed to UV light, outdoor temperatures, or heat above 80°C. Car parts, garden fixtures, outdoor enclosures, antenna mounts, and dashboard clips are ASA territory.
The tradeoff for ASA's performance is difficulty. It warps badly if there's any airflow during printing, which means an enclosure isn't optional — it's required. Even with an enclosure, first layer adhesion can be finicky. A brim (5–8mm) almost always helps. Bed temperature needs to stay high throughout the print, and the chamber temperature ideally gets above 40°C before the first layer goes down.
ASA also releases fumes during printing. The styrene content means you should print it in a ventilated space or with a filter. An enclosure with an activated carbon filter (like those sold for the Bambu X1C) handles this adequately.
On the positive side: once you've got ASA dialled in, it prints with excellent surface quality, very low stringing compared to ABS, and good dimensional accuracy. The functional properties — heat resistance, UV stability, chemical resistance — are genuinely excellent and there's no FDM alternative that matches them at this price point.
When to Use Each: A Decision Guide
Use PLA for: display models, figurines, cosplay props, desk organizers, phone stands, wall hooks (indoors), vases, decorative items, most prototypes, and any functional part that won't experience heat, flex, or moisture. PLA is the right answer for probably 70% of home printing.
Use PETG for: snap-fit joints, cable clips, brackets, hinges, tool holders, kitchen items (dry contact only), sports equipment, parts that get handled frequently, anything going in a moderately warm environment (up to 75°C), and any print where layer delamination from impact would be a problem.
Use ASA for: outdoor enclosures, garden tools and fixtures, car interior parts and mounts, anything exposed to direct sunlight for extended periods, parts near heat sources above 80°C, and anywhere chemical resistance matters (cleaning products, solvents).
If it goes outside → ASA. If it flexes or gets warm inside → PETG. Everything else → PLA.
Practical Printing Tips for Each Material
PLA tips
PLA is forgiving, but a few settings make a real difference. Print slightly cooler than the maximum suggested temperature — 210°C is often better than 220°C for surface quality. Use a part cooling fan at 100% for everything except the first layer. If you're getting elephant's foot (the base layer spreading wider than the rest), reduce your first layer flow or raise your Z offset slightly.
PETG tips
Turn down your part cooling fan to 30–50% — PETG needs less cooling than PLA and over-cooling causes layer delamination. Slow down your first layer speed to 20–25 mm/s for better adhesion. If you're getting stringing, try a temperature tower to find the sweet spot — PETG often prints cleaner at 235°C than at 245°C despite the higher maximum on the spec sheet. Enable combing in your slicer to reduce travel stringing.
ASA tips
Get your enclosure up to temperature before you start printing — pre-heat the chamber for 10–15 minutes with the bed at 110°C. Use a large brim (8mm minimum) and keep the door closed for the entire print. If you're getting cracks between layers, increase your nozzle temperature by 5°C and reduce part cooling to zero. ASA benefits from printing slightly slower than your PLA speeds — 60% of your normal speed is a good starting point.
The choice between these three materials is almost always determined by the environment the part will live in, not the object itself. A hook is a hook — but a hook inside a bedroom drawer needs PLA, the same hook holding tools in a garage should be PETG, and the same hook mounting a camera on a boat needs ASA.
Don't over-engineer your material choice. Most prints don't need PETG — PLA is lighter, prints faster, has better surface quality, and is cheaper. The upgrade to PETG only makes sense when you genuinely need the impact resistance, flexibility, or higher heat tolerance. And ASA is a specialist material — excellent at what it does, but harder to print and more expensive. Use it when the application demands it, not because it sounds more impressive.
Start with PLA. Get comfortable. Add PETG when you hit PLA's limits. Only add ASA when something is genuinely going outdoors or into heat.