The R.A. stepper motor and the bearings to hold the split-ring are assembled with the base part. In order to print the base assembly by 3DP, the base is split into four parts. The should be assembled by sand paper, joint and glue.
The shape of top/bottom view is regular triangle. There is a hole in the center to denote the center the base. I have tried to make the tube's center of mass aligned with this location. This will make the whole structure more stable during operating.
