I think that your view master model is a good direction. Your shutter could be a slit that exposes the film as it rotates when you press the trigger.
Or the film cartridge could be fixed and the trigger rotates a disk with the slit. This might be interesting in that each shot would have a slightly different perspective.
You are going to have to correlate the width of the slit with the speed of advance by the trigger and the focal length of camera for a proper exposure.