Make:

Dave at Pop Sci has a fun motorized paper airplane you can build, he writes -

The single-sheet paper airplanes you made when you were a kid (or perhaps last week in your cubicle) were, well, kid stuff compared to this beefed-up paper craft, which uses an electric motor from an old pager or toy powered by a big electrolytic capacitor. Known as a "Gold Cap" and made by Panasonic, the capacitor charges from a battery pack and then metes out a steady flow of power to keep your propeller whirring for about 10 seconds--just long enough to send the flyer airborne and carry it between 30 and 100 feet. (You can also add a gearing system to squeeze out even more flight time.) We've created plans for an eAT-6 "Texan" airplane and put them here and here to get you started. Just think twice before blindly launching this one soaring over the wall of your cube.