GLOSSARY
PETG Filament
PETG is the food-safe-ish, glycol-modified version of PET (the same plastic as soda bottles). It is tougher than PLA, handles heat and water better, and prints almost as easily.
Definition
PETG is PET with added glycol that prevents the plastic from crystallizing — which is what makes it printable. It extrudes at 230–250°C with a heated bed around 70–85°C. It has a glass transition near 80°C, so it tolerates more heat than PLA, and it absorbs less water than nylon.
PETG is a good electrical insulator, has decent chemical resistance, and is reasonably tough. It is also slightly translucent in natural form, which gives prints a glossy plastic-bottle look.
Why it matters
PETG is the default when PLA is not strong or heat-resistant enough but you do not want to deal with ABS warping. Brackets, enclosures, mechanical parts that need to flex slightly, outdoor fixtures: PETG.
The trade-off is that PETG is sticky on the nozzle and prone to stringing. Dial in retraction, increase travel speed, and dry your filament — PETG absorbs moisture more than PLA and wet PETG prints badly.
Common confusion
PETG sticks too well to glass beds. Use a textured PEI plate, glue stick, or a release agent — otherwise you can chip glass when removing the print.
"Food safe" means the resin pellet, not your finished print. FDM layer lines harbor bacteria regardless of material. Treat any 3D-printed food contact part as single-use.