Sometimes when painting a creature, you will want to bring that "lifelike" feeting to it, and a good way is masking your materials, and colors using nature-like masks. Like animal stripes, zebra, tiger, specks, all of this.
Thinking about that and to fill up my own needs as a texture artists, i created an "all-in-one". Mask generator. Of course it will not cover all kind of animals, but it will give you a GOOD range of flexibility and creation using it.
Using it, just tweaking its parameters i have created 31 presets. You can use then as they are, or just use as a starting pointing to create new ones from it tweaking it and saving new custom parameters to make a bigger personal library of your own.
Drag it to your Substance Painter Materials, as a Base Material, and then drag it into any Fill layer as a mask. This generator only generates Black&White Masks. So the idea is to mask your layers in Painter using its information.