ya lianna i have been thinking that any mechanism that is designed to move the film (whether it is the viewmaster design or the strip of three) is going to be more complex than merely having three simple cameras in one. My rationale for that in addition to a semi-precise film transport, all the seals will have to be light proof. In a lot of ways having three versions of the same thing all ganged together would be easier. As you likely can use a simple meniscus lens, having three simple plastic lenses will not be that costly (compared to making a complicated mechanism) -- they could be molded as one long strip of plastic. Your shutter could be a simple little plastic gizmo that had the 'spring' just be a flexy arm that is part of the shutter. It could be really basic. Again could probably mold all three shutters and springs from one piece of plastic.
There are a lot of multilens cameras out there that are novelty cameras sold by lomography and places like that -- for example http://canada.shop.lomography.com/ca...tilens-cameras
You should have a look at them. They are designed to fire each lens in succession so you get a semi stop-motion effect. I am not sure what you are planning for how you would use this camera but you could probably work out some mechanism to fire all three shots in quick succession if you wanted to have that as an option. Your project seems more fun than the stuff I am working on today ;-p