Thanks, I pretty much took a dark color and used the roller on it at least 3 times, then took a light gray color to brighten it up, then put random spots of different sizes
So yea.
Take a dark color and used the roller on it at least 3 times, then took a light gray color to brighten it up, then put random spots of different size. You may need to use the roller a little bit more than 3 times if necessary.