My old favourite, from scavenged lawnmower engines is the Robot Wars
battlebot. Made a mean twin engined metal chewing monster out of a
couple old lawnmowers.

Went well till the petrol storage leaked and the bot blew up. Sure was
fun though and I took out the competition. Couldn't recognize one
internal component, apart from the engines and the motors. (Which were
twisted to hell and back). Melted polycarbonate and sheet steel
carnage. My name is banned from petrol bot building. Shame, i love the
noise they make.

TR