Compact Disc player integrated in a port-hole of ship. The Play "function" is done simply by closing again the hatchway. When slightly open, it is put in position "pause". The functions of front "forward / reverse" are done by pressing the two rivets of the bottom.
I think it's the best CD player I'ever built. The smallest as well, and the most dificult. It looks very sober and can play even hanging in a wall.