Parametric disc for repurposing plastic venetian blind slats from trash in a small water wheel, Banki-Michell style turbine, and eventually in an electricity generator. First version in SketchUp more than one year ago, I publish it now, converted to OpenScad so you can describe your own slats, change the blades orientation, etc. I'd love to see those disc cut out / milled of unused CDs or DVDs because trash cans are full of them (I don't know if it's possible to lasercut CDs on the non reflective side). Short animation demonstrating some parameters variation : http://vimeo.com/29516070 Reference : http://en.wikipedia.org/wiki/Cross-flow_turbine http://autonopedia.org/renewable_energy/Water/Index_Water_Power.htm