Originally Posted by SOGAmember666
What internals are you wanting to run?
I'm using custom internals - a continuous rotation servo and a digispark (a tiny Arduino clone). The code was pretty simple to have the servo run based on feedback from a flex sensor. I also tried a piezo (vibration) and loudness sensors. I also have some light detecting (eyes) sensors but I haven't had time to test them.
The quarter sized board is the Digispark. The really tiny board is a loudness sensor: