Where each material makes sense

Start with ordinary PLA for display pieces, detailed models and prototypes that mainly need to hold their shape. It is generally straightforward to print, with little warping. Its weak point is not appearance but demanding service: heat and impacts can be a problem. Prusa's PLA guide describes these trade-offs.

Consider ordinary PETG for brackets, holders and parts that need more toughness. It is generally less brittle and more heat-tolerant than ordinary PLA, but may leave more strings and less tidy overhangs. It can also grip some build surfaces too strongly. Check the plate manufacturer's instructions rather than assuming more adhesion is always better. Prusa's PETG guide covers these limitations.

These are starting points, not guarantees. A thin PETG hook is not automatically more useful than a well-designed PLA bracket. For a non-critical part, print a small test in the intended orientation and check fit and behavior before committing to the whole model.

Use a profile for the actual spool

There is no single correct “PETG temperature” or “PLA temperature.” Even Prusa's material table gives ranges. Start with the filament maker's recommendations and the matching printer/nozzle profile. Silk, filled, high-speed and modified blends should not inherit settings just because the label contains the same base polymer.

If strings appear, do not immediately change five retraction settings. Check whether the filament needs drying, then follow its manufacturer's temperature and time limits. A storage box with desiccant is not the same as active drying. Prusa's drying guide explains the distinction.

Two claims to treat carefully

  • “Heat resistant” needs context. For a warm enclosure, car interior or continuously loaded part, consult the exact material's data sheet and test the application. A printing temperature is not a safe operating temperature.
  • “PETG means food-safe” is not a shortcut. The formulation, additives, printing process and finished surface matter. Neither a PLA nor PETG label certifies the finished object for food contact. Prusa's food-contact guidance outlines the complications.

Source: Prusa's food-contact guidance

A practical default: PLA for learning and appearance-first indoor objects; PETG when the part's job calls for more toughness or heat tolerance. If failure could injure someone or cause damage, that rule of thumb is not a substitute for engineering validation.