I am a charter member and treasurer of the MIT chapter of the American Society of Precision Engineering. This group was founded to connect people from several different precision engineering groups as well as exposing precision engineering to undergraduates.
The Hobby Shop Club is a group where students get together and work in the Hobby Shop outside of hours. We also repair machines and offer tutorials. I am a charter member along with Folkers Rojas, Aaron Ramirez, Oscar Viquez-Rojas, and Ilan Moyer.
Next-Make is a group (founded by me, Aaron Ramirez, and Hao Ding) where people based in Next House get together and build cool stuff. So far, we have built a RepRap, a lighting system, and we have given seminars on soldering, Arduinos, using a Dremel to make an Altoids Mouse and how to use laser cutters.
I was a member of the MIT-Harvard RoboCup Team. RoboCup is an autonomous robotic soccer tournament. We basically made little robots that play soccer.