interesting idea...would have to be done in the darkroom like this test since there's no way to get a lightproof seal....unless you cover the entire bottle
lens/shutter could be in the neck...nice idea...I like exploring all possible options.
In fact...it could be pretty funny: making a camera OUTSIDE the bottle, since making it INSIDE is too much of a pain in the ass!!! --- hey, I think I'm starting to like that. I think I owe you a beer for the suggestion.
btw, for everyone who wants to see the camera(s) and images...I'll eventually post something in keeping with my usual glacial speed, but if you're in the DC/MD/VA area, I plan on putting a collection of unusual homemade cameras & their photos in the next Artomatic ( 1,000+ artists taking over an office building for the month of June )
www.Artomatic.org ...there will probably be other APUG members showing there too, I know there was at least 1 in the 2007 Artomatic