This is a great idea. I noticed though, that you have trees in various colors. How do you get this to happen?

When I first tried to use this, I was using transparent brushes, which I have found doesn't work if the density is greater than the very sparse. I ended up layering color behind one, merging down, and making a brush from the clipboard, but the trees all look identical that way. In your example there is at least color variance. Is this a difference in how I am implementing the script, or did you recolor them afterwards?