This is my own design of a 3D printable model of the classical Wells turbine. Turbines of this kind may be operated in bidirectional airflows and are the heart of OWC (Oscillating Water Column) wave power plants. Printing the STL files you'll get a properly designed turbine with an outer diameter of 113 mm and an 8 mm axes bore. To run it, you'd put it on an axis into a tube and power it with an ordinary vacuum cleaner or - better - a leaf vac or with compressed air from either side. Use the 3-blade design for highest airflows (leaf vac) and the 7-blade design for low and middle airflows (house vacs). To give the design a fairly good starting behavior (which is an issue with this turbine type) I used appropriate NACA airfoil data in the blade and cap design. Have also fun with two of my videos showing this kind of turbiine in action as well as more sophisticated newer designs with self adaptive behaviour I'm holding a patent on. I'll try to present models for the newer designs in my further work. Feel encouraged to also leave feedback and comments on these. Air turbines: http://www.youtube.com/watch?v=lRwBGI_o11c Water turbines: http://www.youtube.com/watch?v=Djsl1uou6F8 The SCAD file offers sufficient parameters to let you choose your own sizes, blade number, NACA number and between half and full design, depending on your printing technique. The half design things might print easier on FDM printers. Print an upper and a lower (mirrorred) half and glue them together after print.