Three amateur pilots take on a team of stunt fans in a challenge to build a machine that will allow Richard to feed his dog without leaving his desk. With a place in the semi-finals at stake, the rival teams let their imaginations run wild - and even spy on each other's work in a bid to get ahead. Chain reaction machine guru Zach Umperovitch is the expert judge, while Shini Somara explains the science behind the eccentric contraptions.