I bought a small robotic arm - it was fully assembled with servo motors and everything. But it is fun to play with, using an Arduino. Anyway, the prinicples of inverse kinematics for robotics are the same - no matter how big the robot is. This particular robot used small servo motors, but I also played around with a larger IGUS robot using Stepper Motors which we programmed ourselves as well.
Robot in Action
The robot in action