William Butterton likes to tinker. "I had invention journals when I was a little kid," he told Business Insider. "I always wanted to be an inventor." Through his 20s and early 30s, those ideas mostly stayed on paper. He was comfortable in his day job and didn't feel much urgency to build something on the side — until he had his first daughter. "That's when I started really thinking about how I could bring some extra money in, but without sacrificing that safety net that I had built at my job,"