Before I make the drawing, I shall write down what I wanted:
1. Light weight and short
2. Able to balance for two equipments of different weight
3. Able to take two (ball) heads
4. Able to attach a mobile phone to aid initial polar alignment
5. Able to mount a battery pack on one end for balancing (e.g. 5 AA rechargeable)
Feature (4) and (5) could be done in an ad hoc manner, not necessarily a design time feature.
Anything else? Here's the first draft:
1) Found a 5 * AA battery box, it could be used to provide 6V DC required by the motor, and therefore, this battery box should be fixed on one of the sides.
2) Should also prepare a way to mount a counter weight shaft there in case I wanted later
3) Or buy something like this:
cut the upper part and attach to one side of the plate? It will then allow slow motion control.