This is an electrical appliance that turns an ordinary household door into a fan, provided the door swings freely (i.e., it is not a sliding door and does not catch on the carpet). The device consists of three parts: the base, the transmission, and the arm. The base houses the motor ( which is at floor level so that the unit isn't top heavy) and supports the stand, which is a tube perpendicular to the floor that houses the transmission. The end of the transmission connects to a cam, to which the arm is attached. The distal end of the arm has a clamp which grabs the door edge or door handle.
As the motor turns, the cam rotates and the arm reciprocates, which opens and closes the door thus circulating air about the room.-- Cuit_au_Four, Sep 18 2010 Similar. Door_20Bellows [swimswim, Sep 18 2010] Also good for scaring off intruders. +-- xenzag, Sep 18 2010 Might require some training of pets, children, etc, but a neat idea. [+]-- Boomershine, Sep 18 2010 random, halfbakery