Constantine Zlatev, Kostadin Ilov and Velina Ruseva have taken a disabled shotgun and some salvaged industrial components and created a musical instrument. Called The Last Gun, is controlled by a Raspberry Pi and an Arduino and uses compressed air to play different tunes through the barrel of the gun. Determining what is played is done based on a graph of US arms exports from the 1960s to 2010. If the amount of exports rises, the tune becomes more sombre; if the exports fall, a more upbeat tune is played. You can see more pictures on Constantine’s blog here and watch a video below: