Above is a rough idea of the size. The final design will be very simmer to this just the base will be completely redesigned. Above is my early ideas for the shoulder joint. However with this design there is a huge amount of stress on the gears and the frame holding the two turn tables in place. This design also uses some modified lego parts that allow for clearance with the rotating arm. But I don't what to use any modified lego parts in my design. 
Here I have used 2 stud long rubber bits to work as feet on the base when they are on a flat surface they offer a very strong grip.   

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