What about useing simple timing belts and pulleys that are off the shelf parts for the gear box. I have seen off the shelf bearing mounts that could be used. Maybe a frame for the rotor could be made out of simple aluminum plate or out of something like aluminum extrusion stock and use the slots to mount the bearing holders. You could use multiple large and small pulleys to build the gear reduction up to a sizeable ammount to turn the axixes. You could also look at sprokets and chain drive. Right now their is not a lot of AZ and EL rotors to choose from and they are expensive. The other problem is that when they break parts are hard to come by and expensive and for most people its too complicated for them to repair them self.
Mike Hoblinski
N6IMF