How can I get more of this macro photo in focus?

I want to make a full focus on the body, for example:
I need to have a clear focus on the each balls in the photo. I used just single point focus.

In this picture I used:

• shutter speed: 8


• aperture: F/4


• ISO: 200


• 2 flashes, one in the right and one on the top of project


• camera: nikon d300s


• lens : 105mm micro 2.8

Thanks