He built his own 3D-printed cornstarch flamethrower using a battery-powered leaf blower, a hopper, and a propane torch. Called the The Conflagulator, it blows a cloud of cornstarch at the torch which lights it, turning it into a big fiery mess. Do not try this at home.
Owen is a designer and maker and this project, while wildly dangerous, shows just how much fun you can have with some off-the-shelf parts and some kitchen ingredients. You can check out some of his other projects (including this amazing huge robotic hand) at his YouTube page.