So I am going to use a spare Space Marine. I have him primed blue, but I would normally prime him black.
Okay, First, before we start, we need to talk about light sources. Now, there are a couple of techniques that we can use. All around, 360degree, coming in at a 45 degree angle. Object Source Lighting.
For the most part, I use the 360 degree technique. OSL is awesome, if it is done right. Kind of like this. Remember, we have it coming in from the front and rear of the model as well.
For this tutorial, I am going to use a blue primed marine I have laying around. I did a paint up on the other shoulder pad, but didn't like the way it came out, so I went to the other side and started working in greens.
As the base, I laid down 2 thin coats of GW Caliban Green.
Using GW Warpstone Glow, I painted the trim ring and the inside of the pad. I left a thin line of the darker green to work as the shade. Again, 2 thin coats.
With GW Moot Green, I applied a line to the inside of the pad, right up against the darker green shade line. On the trim, so started the highlight a bit lower, to represent light shining off of it.
Final highlight was a mix of 50/50 Moot Green with Skull White, and applied it to the very tip of the corners of the 2 highlights. Up close, the highlights might look a little chunky.
But from a distance, the highlight does what it is supposed to - grab your attention and pull it to the hightlight.
Every one enjoy!