Here is a WIP pic of the three bases. I painted two of them and the third one is dry now so that I can add crystals to it today.
Here is a WIP pic of the first Space Marine (standing on a desert base later on, with red light from the sunset coming from one side):
Next to it, you can see the colour I use as a base colour for all three of them, and the effect of adding the first atmosphere colour (the yellow I used for the desert base above) to all colours applied. The first layer is desaturated by adding a tiny drop of the complementary colour to the mix.