Limor Fried created MP3 players and other devices while studying for her master's degree at the Massachusetts Institute of Technology. She posted do-it-yourself instructions on the Internet, and the feedback she received eventually led her to start Adafruit Industries, which sells hardware kits that customers can assemble themselves. "I spend a lot of time thinking about how customers will interact with products so they won't break them," Fried said. "And when we sell something, we always give good documentation to get [them] going in a couple minutes."