"What was your yoyo?" is a common question MIT mechanical engineers ask each other because every student in the last 25 years has designed one as part of 2.008, Design and Manufacturing I.

Our yoyo was inspired by the skylines that adorn either side of the Brass Rat, MIT's class ring. To make things interesting, we mounted the skyline pieces on ball bearings so that they could spin freely. It was fun to try to throw the yoyo while keeping the skylines stationary.

Each yoyo half is made of a body, skyline, and outer ring which are all injection molded. The bearing is press fit into a cavity in the body and the skyline is press fit into the bearing. A clear window over the skyline is thermoformed and held in place by the outer ring snap fit onto the body. The halves are connected by a nut and threaded rod that are overmolded in the two body halves. Last but not least is the string!