At the start of the page I was really curious as to what image sensor they'd be using. Then I felt like an idiot.

I think the expectation of digital is not unreasonable, here. Most photos that get taken are taken on digital cameras.

Using a digital sensor would have several advantages in prototyping - you get a faster iteration loop of 'build camera, take picture, evaluate result', you can actually check for light-leaks in real time without removing film, and so on.

You could try to integrate one of these into the project: http://www.bigshotcamera.com/

The only problem is that the sensor is probably tiny and any old lenses you might want to play with would have a massive telephoto effect, making focusing very difficult.

Album with examples: http://imgur.com/a/XzVBq