In the nineteen thirties a German company called Welta was making mid-priced folders like this one and they were amazingly compact. This camera, the Welta Symbol, captures 6×9 images on 120 roll film and yet it is about the size of the latest i-Phone, albeit about 2.5 times the thickness. Considering all the huge medium format cameras that would follow (Pentax 67, Bronica GS1, Mamiya RB, Mamiya Press, just about any TLR) the compact form of this Welta Symbol is rather striking! A friend gave it to me yesterday and I ran some Fuji Acros thru it today but alas, there is a pretty significant light leak. No idea how to go about fixing it either. Oh well.
Chemical Cameras 
Oh no…
Put a glow stick inside the camera and take it into a darkroom, or closet. you should be able to find where it’s leaking, then decide if there’s a way to fix it.