"Hey Pewny, how are you?"
“I’m pretty good. And how about you? Aside from apparently gaining weight?”
“Well, there is a small, high-speed electric engine inside it, with a weight, usually a half-circle shaped, attached to it. The weight spins very fast, the sheer force and speed making the whole thing vibrate.”
"Oh, I see. I wonder if it’s hard to make one of those…”
“Not really. Such small engines can be bought cheaply, and a weight is not a problem either. The outer shell may be problematic.”
