I'm currently messing around with the idea of a steam turbine made out
of 3D printed plastic.
Early design test shows that it's practical, and can meet the goal of
being able to charge a cell phone (5V at 3A like a typical USB 2 charger)
The actual design is on github as an OpenSCAD file: https://github.com/bombasticbob/3DObjects/blob/master/turbine_rotor1.scad
The rendered result looksl like this:
|Location:||Huddersfield, West Yorkshire, UK|
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