Ok...I think I understand. Yes, Carrara has alot to understand about the shader tree. Alot of options. The manual does have information in there.This is not layers list or anything else.Someone could spend alot of time writing tips on that alone. Here is a very simple method to start. Multichannel Mixer--> You get source 1 and 2 then a blender. So say 2 colors and fractal noise as the blender. Or could be 2 textures and a blender. It goes on and on, but try simple first.

No need to think outside the box....
    Just make it invisible.