Apr-15 (BusinessWeek) -- From a Milwaukee office overlooking the original Miller Brewing plant, Craig R. Reiners haggles over futures contracts for barley, the primary grain in Miller Genuine Draft beer. He also negotiates aluminum futures, because the metal is used in the millions of beer cans the company produces every year, and works out more esoteric deals, such as swaps and collars on the natural gas that fires the brewery outside his window. Reiners' job is to insulate MillerCoors from commodity price fluctuations and ultimately protect the Great American Beer Drinker from having to pay more for a six-pack.