Hulling rice
“There was a lot of trial and a lot of error,” Brill said. It took two years for him to crack the huller, during which time he developed a custom spoke mechanism, found exactly the right foam pad in a boat-supply store, and cannibalized various home appliances for parts. He now offers designs for a table-top huller, capable of milling four pounds per hour; a bike-powered version, which can process up to twenty pounds; and a larger one, powered by the motor from a clothes dryer, on which his son was eventually able to process six hundred pounds. > >
I love this story by Nicola Twilley about Don Brill's creation of a cheap rice hulling machine.
What I love even more is Don Brill's video demonstrating how it works.
http://www.youtube.com/watch?v=f86aCfOCeZs