Available from Thingiverse, this print was a mechanical parts test.

While this model required a significant amount of time (and sanding), the turbine is able to freely spin on the two bearings attached to the frame.

With the poor printing tolerances in my inexpensive 3D printer, each gear needed sanding for proper alignment. Each gear nicely aligned with each other once sanding was complete.

In addition to that difficulty, the slicer software would generate extreme vibration about halfway through the print, as it attempted to trace out imperceptively thin vanes of the main fan.