This is a traditional mechanical object in Styria. It is used as bird scarer in the vine yards of traditional wine-growing landscapes.
When the wind blows, the rotor blades and so the shaft start to turn. On the shaft there are some levers which are lifting the wheight on it. When the levers turn around the weights fall down and impact onto the tube. This impact makes a noise.

For example you can use it to make nice noises in the wind or to keep away animals from your garden plants.

You can see a VIDEO here:
https://youtu.be/CQovZbifR9Y

If you need additional blades visit: http://www.thingiverse.com/thing:1498345 Cooasty made a lot different shapes you can use.

Have fun!

You can choose between the traditional straight rotor blades and the enhanced blades, for landscapes with low wind.

You need three M3 Screws (>5mm) and one M5 (~12mm) screw and three pins (d5x8 mm) you can print them too but i took some ready shafts.
I used two ball bearings. (22x8x6mm | Dxdxw) = Bearing No. 608.
You can also print a jack to replace the bearings.

You'll need to make some threads:
You need one M3 thread in the levers and one M5 thread in the back side of the shaft.

The levers should have a distance of 120 degree.

Assemble like in the picture.