Junkyard Wars on TLC

Teams compete to build something that works from objects found in a junkyard. Contestants are assigned to an expert, and are told what they'll build---it could be, say, a street sweeper or a hydrofoil---and they then mastermind a design. The series became known as 'Junkyard Mega-Wars' in 2003, when the format changed from a six-week competition to one in which challenges are resolved in the same episode.