PLA — easiest to print, stiffest at room temp, useless above 50°C
PLA is the easiest material to print on any FDM machine — low warp, low odor, sticks to almost any bed. Stiffness is the highest of the three, so PLA prototypes feel solid in hand. The catch: PLA softens around 50-55°C. A car-dashboard part in Indian summer will deform within hours. PLA also creeps under sustained load — a clip that holds force for weeks will visibly relax. Use it for visual prototypes, fixtures used at room temp, and anything where you'll iterate fast.
ABS — tough, heat-resistant, but a pain to print without an enclosure
ABS is what Lego is made of — tough, slightly flexible, heat-resistant up to ~90°C, paintable, sandable, and acetone-smoothable. The downside is printing it. ABS shrinks ~0.8% on cooling, so a non-enclosed printer will warp larger parts off the bed. ABS also emits styrene fumes that are unpleasant indoors. For Indian print farms, ABS works on Bambu X1C, Prusa MK4 with enclosure, or QIDI / Raise3D. If your bureau is running open-frame Ender clones, don't ask for ABS.
PETG — the practical default for functional engineering parts
PETG hits the sweet spot for most engineering use in India. Stiffness is between PLA and ABS, heat tolerance is ~70°C, it doesn't warp on open-frame printers, and it has good chemical resistance. The trade-off is that PETG prints best a bit slow and stringy if temperature isn't dialed in. A bureau that knows their PETG profile gives you reliable parts; a bureau that doesn't gives you stringy, weak prints. Always ask for PETG samples before committing to a batch.
Quick decision matrix
Visual prototype, room temp, fast iteration → PLA. Outdoor or warm enclosure, snap-fits, paintable cosmetic part → ABS (only on enclosed printers). Functional engineering part, needs some heat tolerance, prints on any machine → PETG. UV-exposed, high-temp, or load-bearing for years → step up to ASA, Nylon, or Polycarbonate. Watertight, fine detail → step laterally to SLA resin. We default to PETG when a client doesn't specify, and we've yet to see that decision regretted.