Killer Sound Posted by Kevin Sites on Mon, Apr 24 2006, 1:58 PM ET Colombian musicians turn guns into guitars to make music - as well as a point. BOGOTA, Colombia - It's not long after you enter the world of Cesar Lopez that you realize he doesn't color inside the lines. He is a classically-trained musician and composer who studied at Colombia's best conservatory. But instead of concert hall performances he chooses to play his music on the streets of Bogota. He writes all of his songs on air-sickness bags he collects during his travels. "It's appropriate," he says,...