The 12-year old Wales High School pupil put in hours of work to come up with an invention designed to transform the life of his mum, Sarah Kilner, who has a disabling condition.
In the first ever Imagination Awards, launched by the West End production of Charlie and the Chocolate Factory, Lewis created his design for Supreme Robo-Legs.
Judges including director Sam Mendes shortlisted his entry to the final 10 and Lewis could now win prizes including a VIP trip to London.
Lewis told the judges: “Supreme Robolegs would be great for my mum and help her mobility. My mum has Ehlers Danlos Syndrome which meant that she lost much of the use of her legs. Supreme Robolegs would change my mum’s life.”