When you hear about building robots, you probably imagine the complexity of the process. But his is not always true. It depends on what is your aim. If you want to construct a precise manipulator or even humanoid, then this requires quite some science and research. But don’t get caught with such idea that things are always complex and difficult. Mizchief100 built his Altoid robot using minimum effort and yet it is cool to experiment with.
Robot chassis is assembled on single sided prototype PCB with Arduino chip as heart. Robot is driven by two tiny motors along with L293D motor drivers. Sensor bouquet consists of 2 photo-resistors and microphone. Couple RGB LEDs add some personality. This is enough to make it pretty autonomous. You can play with light sources, voice. If there isn’t enough you can keep adding sensors to it, just be sure to leave space on PCB for additional features.