[Kitsa]

The natural stuff is pretty limited in scope...the red is kind of magenta-y, the yellow is kind of mustard-y, and the blue is sort of purple-y. Makes mixing a little more of a pain if you're going for a wide variety of colors. You can do it, it's just harder and it relies more on a pure-white substance to be colored (rice, yogurt, sour cream, cream cheese, etc).

The artificial stuff can make it easy...I can even do stuff in neon colors if I want.