See actor Kellan Lutz’s patent for an air flipper workout device
Actor Kellan Lutz is best-known for the Twilight movies and for his role in The Expendables 3. But he also invents in his free time.
Though he has a background in chemical engineering, his sole patent is for a workout device that uses air resistance.
The device attaches strips to the hands and feet and, presumably, you move them very quickly. The patent application states portability as a key benefit of the device.