Ask HN: how to start a hardware-based start up?

Hello, It seems like there's a much lower barrier-to-entry when it comes to creating a web-based or other high-level software-based start up. So what about a hardware start up? I have some experience with circuits, processors, and microcontrollers/embedded systems, but I'm not sure where to start when it comes to ideas. I don't think it's possible for any one individual right now to jump into the handheld devices market, though I've always thought making smaller more affordable computing devices would be great.