The teams compete to construct a skyscraper and a metre-long bridge that will withstand a weighted dumper truck . This episode's guest is comedian Rob Beckett.

The seven teams do battle in a drop test to see which model gets smashed up the best. They also build a memorable scene from history. Joining the judges is comedian Paddy McGuinness.

The teams compete to build a hybrid land and sea animal and a life-size crazy golf feature. Comedian Chris Ramsey tees off as this episode's celebrity guest judge.

It's the semi-final. The teams create a bust of comedian Johnny Vegas. Can they capture the essence of Johnny in plastic bricks? They also build a life-size arcade game.

The four teams build a walking-talking robo-pet. There is also a Master Build using as many as half a million bricks. But who will be crowned the winner for 2018? With guest judge Sue Perkins.

Six young builders from previous shows team up with celebrities to do battle in a range of festive challenges, including Rob Beckett, Warwick Davis, Joel Dommett and Alice Perrin.