When Kelvin Doe, a then-13-year-old from Sierra Leone, saw that off-the-shelf batteries were too expensive for the inventions he was working on, he made his own at home. Kelvin did not have the privilege to do his project in a school environment. Rather, he was compelled to act by necessity and for the joy of solving practical problems. Kelvin combined acid, soda, and metal, dumped those ingredients in a tin cup, waited for the mixture to dry and wrapped tape around the cup to make his first battery. He hasn't purchased a battery since. Next up: A generator. Kelvin made one of those by hacking an old rusty voltage stabilizer he found in a dustbin. In addition to providing electricity to his home, where neighbors come to charge their mobile phone batteries, the generator powers Kelvin's homemade FM radio station, fully equipped with a custom music mixer, recycled CD player and antenna that allow his whole neighborhood to tune in. Now 16, Kelvin has expanded operations: he employs his friends as reporters and station managers, tasking them to interview spectators at local soccer games and keep the calendar of requests for his DJ services at parties and events. The average age of his crew is 12. Kelvin ... was at the 2012 World Maker Faire held in New York at the end of September. He was invited to participate in a Meet the Young Makers" panel with four other amazing young makers from America. He is the youngest person in history to be invited to the "Visiting Practitioner's Program" at MIT, and he presented his inventions to undergraduate students at Harvard College and MIT.