The other day I made a robot out of some KNEXs, a few household supplies, a two-color LED, and some electronics.
The KNEX motor turns the wheels making the robot move. Adjusting the switch on top of the robot makes the LED turn red or green. Later I may add a third option that makes the light mix the red and green light together to make yellow.
Top 
KENX moter 
Wiring 
Close up 
Duopersonality good 
Duopesonality bad
Well done Adrian! That is electronics for you! In South Africa, there are robotic clubs, and if you had lived there you could enter competitions! Do you have such clubs where you live?