HN'er DanielBMarkham's daughter talks about her vending machine business [video]

Product and place is probably most important. The ones I use are usually behind the checkout line at toy stores. But there are other interesting areas where the concept can work. For example there are some in my local library with earplugs inside. All the way to certain durex based products in certain rest-rooms. Nothing holding her back from vending machine world domination ;o)

You could do A/B as simple as just switching out the candy that is in the machine, have her track which candies sell well in which areas and try to find the most optimal product that fits into the existing machines for that location. I have to say that it was an awesome video to watch, my kids are still a little too young to actually start on the path, but I do talk to them about the freedom of being self employees and that it is a good aspiration. I really wish I would not have had to learn that lesson on my own.