I'm more concerned about someone inventing a vending machine that doesn't use those piece of shit curly things to spit your stuff out. I've been denied my refreshment three times in a row when they jammed. Clearly they have failed to address this problem.
Haha. Touching story, but that is beside the point. The main idea is to create working and simple Bitcoin powered vending machine.
That spiral feeder you talk about is industry standard in machines like this. Smart heads need to design easy system to prevent double spending first.