Nice shading you got there. Illuminate it. To give it a samurai head, simply add a horn to a helmet with like a squarish thing on top of the head. Add armor to your robot shoulders and make the legs big and strong. When making chibis, make the head as big as the body. Robot eyes have 3 types of shapes: Triangular/Cresent, Rectangular/Polygonal, and Circular/Round type. You don't have add a mouth to it. My mouth is mechanical. I'll probably write a tutorial on mecha design.