I co-designed a remote-controlled robot with my friend Michael Carvajal for the annual 2.007 competition. Although we designed the robot together, we each machined and and assembled our own individual robot from stock materials.
My robot consisted of two components: the car and a torsion-spring loaded device called the "arrow mover." In the 2.007 competition, there were arrows that acted as multipliers for your score. My strategy was to rotate the arrow to 90 degrees to maximize my score (so that the arrow pointed to a 4). The arrow-mover was designed to be placed on the bins at the end of the table using a pulley mechanism, and linkages on the arrow-mover locked it into place after actuation.