In the past few years, we have covered a whole host of awesome robotic arms here. Dexter happens to be a DIY haptic robotic arm with modular end effectors and 50 micron repeatability. The robot is 3D printed and has 5+ axis movement. It is fully trainable.
Dexter uses five NEMA-17 stepper motors with 3 harmonic drives. It can be trained to playback specific paths. The Dexter Development Environment is based on JavaScript. You can find out more about this project here.