This ingenious little camera is capable of making photos in 3 formats on 120 film. By changing the position of integral mask segments inside the camera, the user can choose from 6×9, 6×6 or 6×4.5 cm negative sizes. Here the camera is shown with both mask segments in place, for the smallest negative size.

On the hinged door on the back, a slider reveals the correct film window to use for each negative size. There is no way to change the format after loading the film so there is an area on the back of the camera where the user can indicate the chosen size with a pencil.

Guide lines in the viewfinders allow the user to frame images for the appropriate format.

This Balda Dreibild Box camera came with an artificial case, typical 1930s German production. In my experience it is more common to find cases like these for box cameras in Germany versus the USA.

I took these photos using the 6 x 6 cm format. 12 photos per roll.

Here is the original manual for the Balda Dreibild Box.