My idea was to have the robot's eyes light up by squeezing his hand. To do that, I used the following modules: battery + connector, power, wire, pressure sensor, and two RGB LEDs. You can adjust the color of the latter by using the included mini Phillips screwdriver and adjusting a little control on the module to make it more blue, green, or red.
Note, to make a circuit, all you need is a blue (power) and green (output) part. Pink and orange are optional.