I’ve said it once and I’ll say it again: I, For One, Welcome Our New Quadrotor Overlords.
This video shows three quadrocopters cooperatively tossing and catching a ball with the aid of an elastic net.
To toss the ball, the quadrocopters accelerate rapidly outward to stretch the net tight between them and launch the ball up. Notice in the video that the quadrocopters are then pulled forcefully inward by the tension in the elastic net, and must rapidly stabilize in order to avoid a collision. Once recovered, the quadrotors cooperatively position the net below the ball in order to catch it.