My sister's friend brought a microwave oven once and started making grilled cheese sandwiches during recess. He was told to unplug and never bring it again, but it was not confiscated.
My classmate brought a super-sized calculator to class for tests, as he had a medical condition which allowed him to bring "a calculator". The buttons made a lot of noise but, again, it was not confiscated.
Can children bring in portable hifi systems? What about those squeaky chicken toys? Or a water pistol?