For me, its camera and the SCME
SCME stands for "Sweetest Camera Mount Ever", it was dubbed that by the rest of the team. It essentially looked like an erector set attached to the side of our robot
i was $@#$@#$@#$@# proud of my handy work
it was based on the stock camera mount, modified for 2 axis rotation. Problem, since it was my rookie year, i heavily underestimated how much abuse it would have to take. It broke our second time out due to auto code error and some rough driving.