The top gets hot so I would not place anything that is plastic or cannot handle the heat. To give you an idea of how hot it gets, we place our plates or bowls on top to warm them. It possibly could burn someone depending on how long it's been on and at higher temperatures. Under the unit gets warm but not hot that we've noticed but depending on your counter material (ex Formica) I would take precautions like place some kind of barrier like a silicone "hot pad".