Links
13 Levels of Beatboxing: Easy to Complex | WIRED
youtube.com
2005 Female World Beatbox Champion Butterscotch explains the art of beatboxing in 13 levels of difficulty. Starting with just the bass drum, Butterscotch layers more and more vocal drums and instruments on top of each other until she starts adding real, live instruments as well.
There was a time in my life where vocal percussion was a major hobby as it fit into my a cappella participation in college. Great video that shows the lay of the land from a master.