The teams are challenged to make a walking machine: the winning contraption must carry the whole team and a heavy safe across a haphazard obstacle course.

The challenge is to build a salvage machine capable of raising a Mini from the bottom of a murky lake and park it safely in a car park.

The first of the Scrapheap Challenge semi-finals, where two teams are challenged to build a vehicle to travel as far as possible on only a cup of petrol.

The teams are asked to build a yacht, but not one for the high seas - a land yacht capable of carrying the entire team. The winners will sail through to the semi-finals.

Robert Llewellyn and co-presenter Cathy Rogers unveil a doubly hard challenge - build a car that thinks it's a boat!

In this episode the two teams must create fully functional cannons

In this episode the two teams must make a machine capable of flight.