When you're ready to move beyond simple display models and print something that has to actually work, you'll face a choice between PETG and ABS. Both are engineering thermoplastics used for parts that need real strength. But they behave very differently in a printer and in the field, and picking the wrong one wastes time and money.
The decision comes down to what your part needs to survive. Heat? Impact during use? Outdoor exposure? Indoor mechanical stress? Each material has a specific job it does well.
Heat Resistance: Where ABS Wins Decisively
ABS can handle continuous temperatures up to around 80-100°C without softening or losing structural integrity. PETG starts to degrade noticeably above 70-80°C. If your part will live near a heat source, inside an enclosure that traps warmth, or needs to withstand repeated thermal cycles, ABS is the right call. Electronic enclosures, parts near motors, automotive dash components: these are ABS territory.
The tradeoff is immediate. ABS warps like plywood in humidity. Getting one off the bed intact requires an enclosed printer, a heated bed cranked to 90-110°C, a completely level build surface, and careful attention to cooling rates. The material also releases strong fumes that stink and aren't good to breathe, so you need proper ventilation or a sealed chamber. PETG never makes you deal with this. Bed temp is 70-80°C, it prints in open air, and the smell is minimal.
Impact and Durability: PETG's Practical Edge
PETG has better impact resistance than ABS in real-world use. It doesn't shatter under sudden force the way ABS can, and it has excellent layer adhesion. If your part will be dropped, knocked around, or subject to vibration during operation, PETG absorbs that punishment better. Protective cases, mechanical brackets, enclosures for equipment that gets moved frequently: PETG is more forgiving.
PETG also resists water, chemicals, and environmental humidity without degrading. If the part sits outdoors or in a damp workshop, PETG holds up. ABS is vulnerable to UV damage and will become brittle and discolored after months of sun exposure.
The catch with PETG is cosmetic. It scratches easily during finishing or handling, and it strings badly during printing. You'll spend time cleaning up bridges and stringing with a heat tool or knife. ABS can be smoothed to a glossy finish with acetone vapor, giving it a polished, professional look. PETG never achieves that aesthetic.
Bed Adhesion and Print Difficulty
This is where the daily experience diverges sharply. PETG sticks almost too well to the print bed. You need to let it cool completely before removal, and even then, removal can be difficult without damaging the part. This is annoying but beats the alternative.
ABS fights the bed. It warps because the outer edges cool faster than the core, creating internal stress. Warping starts on the first layer. You need a brim or raft, a perfectly tuned bed, and patience. First-layer adhesion is a constant battle. Most prints fail not because the design is bad, but because the part lifted mid-print.
If you're running your printer in a workshop without climate control, or if you're not obsessive about calibration, ABS will frustrate you. PETG is much more forgiving to operator error.
What to Choose
Choose PETG if your part is mechanical, outdoor-facing, frequently handled, or needs to absorb impact. Choose it if you value print reliability and don't need heat resistance beyond typical room temperature plus a margin. Most rapid prototypes benefit from PETG's toughness and ease of print.
Choose ABS only when the part lives in heat, and you have the printer setup and the operator skill to manage warping and fumes. Automotive parts, high-temperature enclosures, prototypes that sit next to motors: that's when ABS justifies the effort.
For most mechanical prototyping work, PETG wins. It prints reliably, survives actual use, and doesn't demand a perfect printer or perfect technique. ABS is the specialist material for the specific case where heat resistance matters more than everything else.