To make the cameras, Hamburg's sanitation department agreed to let a hole be drilled into the side of 1,100 dumpsters. The dumpsters are then rolled into place, a large sheet of photo paper is hung inside, and the lid is shut. On a sunny day the exposure time for a photo can take as little as five minutes, but on cloudy ones, the workers may have to wait 90 minutes, giving them plenty of time to speculate on how the image will turn out. The photos are then developed in a special lab, and as you can see, the results are pretty spectacular.
Below, the results. See more on their Flickr page: