Source: http://gizmodo.com/3d-printed-syphon-makes-sharing-drinks-impossibly-easy-1491689174
Anyone who's ever emptied a pool or stolen gas from a car's tank knows how a siphon works, but that doesn't make this 3D printed Wave toy seem any less magical. Seeing it in action you'd assume there was some kind of sorcery involved here, as one side of the Wave draws liquid to the other until both glasses have the exact same amount of liquid. But it's just well-known scientific principles at work.