Based on a sx70 back + the front lens and shutter or a 6x9 french camera from the late 40's called the"sporting".
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The obturation speed is unknown but seems to fit with the 600 film. Good news.
Another monster in my collection.
first test shot here »
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this Sporting camera is made out of cardboard, wich makes it easy to cut and build. Two viewfinders for both landscape and portrait on top of the camera. I used the body of the camera to rebuilt it.