DIY: a paper, pinhole camera

http://paperforest.blogspot.com/2005/06/working-paper-pinhole-camera.html



And here you have another:
http://www.exploratorium.edu/light_walk/camera_todo.html
also nice :)

If you like to project the outside world into your room, try this one.


Old plans to build your own, cardboard, camera obscura: here.