Registration for the O'Reilly Artificial Intelligence Conference, June 26-29, 2017, in New York is now open. Recently, I set out to install a doorbell in my new house and thought: why doesn't my doorbell tell me who is at the door? Most of my DIY projects end up costing more than the equivalent product, even if I value my time at $0 per hour. Something about supply chains and economies of scale, I guess. In the course of this project, I built a door camera that is not only way cheaper than my Dropcam, but it has some genuinely useful features that, for some reason, aren't available on the market yet.