The "box" was created by Eastman Kodak in 1888 for the film reel. The shape he was probably inspired by the "detectives" bigger "clubs" born earlier in France for photography on plates. Here, the film bypasses the unit and the rear face allows the film to get flat face optics. This is the reel will contain the exposed film.
The idea was to make photography simple: aim, push the button and move the film. Little or no adjustment at the beginning: a small aperture for maximum depth of field and a fixed speed for freehand snapshots.
There were box of any size depending on the film. Although the first box Kodak gave 100 views the circular size of 65 mm diameter, the roll of film in the format 620 and 120 give views 6 X 9 cm which was the most prevalent.
Some were more advanced box by more convenient visors, optical higher quality to windscreen or adjustable diaphragms and by more efficient shutters. These once synchronized shutters allowed the addition of the flash.
The shape of the Box was also varied by rounding the corners and leave the strictly cubic shape; construction was cardboard, wood, or metal covered with leather or black color or bakelite or other plastic material; front facades were also decorated with designs and trendy colors.
The Box has actually put photography in the scope - both technical and financial - of all and both say they have been produced in large numbers around the world...