I’ve attached a quick workflow of the gun modeled for the space soldier.
It was essentially done with a combination between shadowbox and simple shapes to create sub objects.
As far as Guy, he was created from a base mesh from Max, the hair was extracted from the head. The belt was made pretty much the same way as the cylinder parts of the gun. It was just reshaped after it was modeled in radial symmetry.
The ring was shadowbox’d, and refined with the planar/clipping brushes.
His logo was an alpha on a plane and then deleted what wasn’t in relief.
The render was pretty much identical to the AMAZO comps.
I hope this helps… if not there are some great youtube tutorials posted by pixologic from some amazing zbrushers.