If boredom sets in over the holidays, take a page from some freshmen engineering students at Johns Hopkins: try to build a racecar powered only by two mousetraps and six rubber bands.
Many of the students went with wood slabs for the body, and there were more than a few wheels made of DVDs. The cars needed not only propulsion but also maneuverability: they had to navigate an 11-foot-long curved course and somehow slalom around two sand-filled soda bottles blocking the way. The winners hit on an ingenious solution: they attached rods to the top of their cars, and when the rods hit the soda bottles it forced the front wheels to turn, steering the cars around the obstacle.
But words do not to justice to these feats of engineering: watch the video. Best rubber-band-and-mousetrap racecar at your holiday gathering wins an extra piece of fruitcake.