From Wikipedia: "The bullroarer, rhombus, or turndun is an ancient ritual musical instrument and a device historically used for communicating over great distances. It consists of a piece of wood attached to a string, which when swung in a large circle produces a roaring vibration sound."

Just print, then tie a string to the end (securely), and spin! It takes a bit of practice, but when spun, this model catches the wind and makes a "roaring" sound!

No supports needed.