The following materials are banned for safety reasons, because they give off highly toxic fumes, are a fire risk, or may damage the machine.
PVC/Vinyl - releases Chlorine which will damage the laser
Polycarbonate
ABS
Polyethylene (PE / HDPE)
Styrene / Polystyrene / HIPS
Polyethylene (PET / PETG)
Nylon (PA)
Treated or coated real leather
Vegan leather
Epoxy and similar resin materials
Carbon fibre composite
Fibreglass - both raw glass fibre and finished composite
Any other material containing Bromine (Br), Chlorine (Cl), Flourine (F), or Iodine (I) in its chemical formula
Any other material containing a CN bond (Carbon-Nitrogen) in its chemical formula
Any other material advertised as fireproof / flame retardant
Any metals, other than engraving anodised Aluminium
Food - do not eat anything out of the laser cutter