A whirligig is a yard ornament, often shaped like a bird, with two spinning propellers shaped like the wings. There are more complicated, animated versions which can look like a paddleboat, or even a man cutting or hammering something. These wind-powered ornaments are simple enough for you to build on your own; a good way to get started is to create a design.
Sketch the design of the finished piece. A typical whirligig has a body and two wing-shaped propellers on either side of the body. For example; draw a body of a bird with two wing propellers on either side.
Draw a shape for the base of your whirligig. Draw an image of a simplified bird in silhouette, including dimensions of the size and width of the bird, perhaps about 12-inches from beak to tail, and a body about 5-inches wide. Detail where the axle for the wings will attach.
Design a pair of feather-shaped wing propellers. The propeller has a length of dowel between two feather-shaped paddles. Draw a template for one feather shape, which you can copy four times. Design the dowel, six inches long with a pair of angled notches to hold the feathers perpendicular to each other.
Design the axle of the bird. It should have a washer on the inside and outside of each wing, and about 2-inches of dowel on either side between the body and the wing. It should have an "HH" shape; two capital 'H's.
Trace your whirligig model plans in pen. Erase any stray lines on the drawing to finalise your design plan. Make full-size copies of the pieces to make templates with, then cut your design out of wood and assemble the whirligig.
More complex animated windmills, which you can make with practice, should have a base, the axle connected to a front-mounted propeller, and the animated parts on top.