Which could keep a high temperature surface cool: Metal or Plastic?
Plastic is a thermal insulator. Metal is a thermal conductor. If you want to conduct heat away from the surface to cool it, then metal is better. If you want to insulate the surface to protect fingers when touching, then plastic is better. Plastic, as an insulator, will resist heat loss from the surface, so the surface temperature of the object might increase, but the surface of the plastic will be cooler than would be the surface of the metal. These comments assume that the hot surface is hotter than the environment into which the plastic or metal will face.
