K'nex Turbo Jet 2-in-1 Building Set
2-in-1 build a supersonic jet, then build a heli-plane with rotating propellers. Over 400 K'Nex rods and connectors are included, plus a battery-powered motor. Build a jet with motorised, rolling wheels and an open-and-close cockpit. Then take it apart and build a heli-plane with working, motorised propellers that you can adjust to spin vertically or horizontally.