Boomerang.

Someday you will find yourself standing on a sun washed field, a freshening breeze in your face, wishing you had a boomerang in hand just to see if the rumors are true.

Engineers call the boomerang an unbalanced airfoil, with one side flat and one side curved like an airplane wing.  Thrown into the wind the spinning boomerang will arc out and gradually curve.  As it slows it will head back toward you, and if you are lucky will slow to a stop above you and drop into your waiting hand.

Thrown improperly the boomerang will arc up and up until it reaches a great height, where upon it will come accelerating back toward you causing you and your friends to scatter to safety, lest this whirling harbinger of doom hunt you down and deliver a mighty blow.  I got whacked once or twice back in the day, much to the merriment of my brothers.           

Such a simple little machine that lets us ride the winds of physics, all the way home.