This is the amazing spinning disc that makes light dance. It spins for more than a minute, very noisily, giving off wonderful reflections when the light is right. Gradually the oscillations become faster and faster until they are no more than vibrations. And then, unimaginably suddenly, everything stops. All observers are transfixed.
P.S. I borrowed the picture from Hawkin's Bazaar. They sell it too, but don't do quidco and I think charge for P&P.