Price: £199.99 One of the best optical illusions we've ever seen, this magic box can make it appear like water is drifting slowly upwards before your very eyes. You can even place a clup in the stream of droplets, and it will simultaneously fill up while the water appears to float out of the top. Unfortunately, this isn't an early home ant-gravity device. The effect is created by a mix of strobe lighting and precise water dispension, and it's absolutely mindblowing. Still, at almost £200, this is a very expensive parlour trick if you just want to impress your friends.