Thiago Olson, a high school student, managed to build a fully-functional nuclear fusion reactor in just two years. Now that's a cool gadget
not many can make at home.
In November 2006, a few tiny bubbles in his neutron dosimeter told him that he'd achieved success: Fusing hydrogen nuclei into helium. While it takes far more energy to run than it produces, Olson's nuclear reactor is pretty bad-ass, producing 200 million-degree plasma at its core -- or, as Olson points out, "several times hotter than the core of the sun.:"
[via DiscoverMagazine - Wired]