Rotary Stewart Platform
All my projects & progress are available at marginallyclever.com.
This is a Stewart platform. While it is very similar to a delta robot (see my other creations) this one can roll, pitch, and yaw for a full 6 degrees of freedom. You could put in a pen and draw on an easter egg, add a dremel and carve tiny sculptures, or a nozzle and print 3D shapes impossible on a makerbot.
This particular kind is a rotary platform because the "arms" have an elbow - the shoulder turns, which pushes the elbow, which pushes the wrist. I have also built a model with linear actuators (no elbow required).
A curious factoid: the mathmatical principles to calculate the angle of the motors are the same used for the spider bot and the delta3. Convenient!