The teams have to build a funfair with at least one spectacular supersized mechanical ride. And they have to build a vehicle out of the blue. Richard Osman guest judges.

The remaining teams head for the great outdoors, competing to build the best brick display in an Essex wood. There's even a Madagascan crocodile. Guest judge is comedian Bill Bailey.

It's the final stage of the contest and the brick builds include a robot with an ostrich head and an alien from the planet Zorg. Guest judge is comedian Dara Ó Briain.