Proceed with depicting details.
I wasn't satisfied the coil of the neck I had drawn first, so smeared away and redrew new one.
Add surface cracks.
Although my image for the cracks of SechsÃ…f protectors and Blade are like brand-new abrasion and cuts, I wanted to express a look that the robot got hit and dented...
So I made it blend with the "Blender" brush to give them a look like this.