Update 2014-0610: This is the updated and finished version of the one piece printed eggbot. Did some changes around the right side idle shaft, to have room for the egg holder cup. This will house a normal size egg or a golf ball. Mine works mechanically just fine. I'm still fighting with the software.
I'm using two 625-2RS bearings, pressed into the housing's right side barrel. The egg holder suction cups are from the well known suction cup toy darts. I used M4 screw and nut to secure the pen-upright to the stepper motor shaft. You've got to make sure that the shaft/screw that holds the pen arm upright and pen arms together will not add wobble. I recommend using a smooth screw, with threads only at the end. I'm using a HEXTRONIK HXT 500 servo. The upright arm will house a Hitec HS-55 servo too, but for some reason it was wired backwards so I swapped it for the hextronik.
The arduino mounts directly to the frame. You can run the stepper motor wires within the printed frame.