Engineering enthusiasts from around the UK competing to create the best chain-reaction machines from everyday objects. In this episode, three brothers from Somerset and a team from Loughborough University are challenged to build ingenious devices that will allow Richard to straighten his duvet and "make the bed" without leaving the bath tub. Machine guru Zach Umperovitch is the expert judge and Shini Somara fills in the science behind the teams' eccentric contraptions.