In this video I will explain to you how you can control the colors with the 3D brushes.
The 3D brushes are able to take on two colors at once, since we are working with dual brushes. You basically have to brush shapes in two different colors, that overlay and create a 3D effect. You can control both brush shapes using the primary (base) color and secondary (top) color.
👉 You also find an explanation on this, inside the Brush Pack Manual