As a gimmick I made a set of three helicopters, all in red and zinc coloured Meccano to take along to the Henley gathering in August 1999. They were based around models that Meccano France was making. In essence I was poking fun at the rainbow of colours that Meccano France used to produce sets in:
The helicopter above used an electric motor to turn the two rotors.
The next helicopter had a crank on the side which spun the main and tail rotor.
When you pushed the last helicopter along the ground the two rotors turned.