I made a chairswing in my class, but I guess that is too easy. How about a ride like Midnight Express?
You would have the cars free swinging. Then the center bar runs along a runner, and is attached to a spinning center. The center bar is attached to the spinning center by a hinge.
Love it. I still love arriving at Thorpe Park with my friends, and pointing out which one is which as we drive through the car park. Also I love pointing out when the rides are going. It's a lovely experience. :--D