Babot is a beautiful DIY balancing robot that uses computer vision and a Raspberry Pi to balance a ball on its surface.
A camera placed under the transparent surface detects the position of the ball. Then a raspberry pi runs a PID algorithm to tilt the plate in the right position using three servo motors.
Babot will be delivered with all the necessary parts for its assembly. Moreover the Python code will be completely open source so you can modify it to make Babot do exactly what you want.