This project has two parts: The first started out as a "boost gauge" for a car; that is, it was intended to give information about the state of the car engine while it was boosting. Currently it consists of a temperature sensor combined with a dial gauge and an LCD display to show the driver the temperature at a particular part of the engine. I also wrote a separate Arduino program which uses the LCD display and a pushbutton to run a simple game. It seems simple but is difficult to win! I am at Table 23.
The second project was a 3D printed arduino powered self balancing robot. Creating it with little to no building materials was very challenging but we have a working (albeit not finely tuned) self balancing robot! The 3D printed parts we printed on-site during the 24 hr time period.