Polystyrene Foam: A Fire Waiting to Happen
Can you laser cut polystyrene or Styrofoam?
No. Expanded and extruded polystyrene foam doesn't cut — it melts, shrinks away from the beam and readily catches fire, and it gives off styrene fumes as it goes. Solid polystyrene sheet behaves little better, melting into a sticky flammable mess. It's a fire risk first and a fume risk second.
Hides inWhere it turns up
Packaging foam and void fill, insulation board (XPS/EPS), foam craft blanks, disposable cups and food trays, model-making foam sold loosely as 'foamboard' (check the core — some is polystyrene).
InsteadSafe alternatives
EVA foam for props and modelling (it lasers cleanly — see the EVA foam guide). Paper-faced foamboard with a genuine paper/card core can cut, but test a corner and watch it like a hawk.
If it happensAccidental exposure
If foam ignites, kill the beam and smother with the fire blanket — don't fan it. Ventilate fully once out. Scrape cooled melt residue off the bed and check the lens.