A mini wind turbine project. The blades with rotor were taken, but modified, from larsonmattr's Mini - Wind Turbine. https://www.thingiverse.com/thing:4941

I added a motor holder, tower, and base. All parts are pressure fitted for convenience, except where the top of the tower meets the motor holder, by design I allow the motor holder to rotate with strong winds. If a fixed position is desired, it can be easily modified with some glue. The motor opening is 15.2 mm x 19.8 mm, and rotor will accept a 2 mm shaft diameter.

Note: The base is a tight fit. However, with some effort, you should be able to get it locked down with the tower perfectly perpendicular to the base. The two pieces that make up the tower are much easier to connect. Your mileage may vary based on your printer's specs but you may need to adjust the connection slightly. If too big, scotch tape should work to make the fit tighter. If too small, a bit of sanding should work.

Update: Bacheporo has graciously modified the rotor hub to allow for clock-wise rotation. http://www.thingiverse.com/thing:1858426