Make a Ball Mill in 5 Minutes : 4 Steps
Wiki says "A ball mill is a type of grinder used to grind materials into extremely fine powder for use in paints, pyrotechnics, and ceramics." Many instructables refer to United Nuclear Ball Mills. Their small ball mill cost between 70 and 80 dollars. For no more than 30 and in 5 minute you can build a ball mill of appreciable performance.