Re: FemShep n7 Armor: SYNTHESIS (ME3)
I tried to take several pictures of my painting process. Using acrylic glazing medium over the spraypaint. If you have an airbrush, you can get a very similar effect with a lot less layering and dry-time. Also you can do this on foam, but seal it well with primer.
I could not find a spray paint silver metallic in the exact hue that would go with both my undersuit and carbon fiber (which are different grays), so that is one necessity for mixing my own and using a roller.

The fact that I clamped this offcenter is distracting, but don't worry, it's not glued yet.
There were two things going on here - contouring, and a little bit of subtractive weathering. When you use glaze medium, it creates transparent layers, allowing you to make a soft hazy definition of 3-d forms (don't use a brush with stiff bristles btw). The render artist probably did the exact same thing in the model, but without the depth that glaze delivers (in computer shading, shadows often look like black smudges sitting "on top" of metal).
Because you're looking at a photo of this you basically just see the soft-focus contrast, almost like the effect from an air brush. If you were to see it in person you'd be able to tell this blends with the metallic underlayer, so that luminosity is preserved.
Also when the medium is damp, you can work subtractively, because it saturates the paint and will lift it off. This can be really frustrating if you're not used to it. But if you happen to have light base - the styrene was white - you can get nice transparent marks. Here I stopped to let this layer dry before I go back and do just a tiny bit more weathering. You can see the only thing I've done here is dig into the paint - there will be a lesser ratio of applied weathering. My goal is for people to not see the marks unless they are standing somewhat close to me, because I don't feel like tampering with the vinyl areas, and it would look weird to have super-shiny carbon fiber next to busted metal.
The boobs are by far the hardest part of hand-painting this costume, everything else is small or separated by negative space.