https://www.youtube.com/watch?v=G8P9PX7WDL4
http://www.foamsmithing.com/guides/rocks-and-spellballs/
https://docs.google.com/document/d/1DLGgxWwL3hW2R43lmQkltu7i-4XGYvQBPaujDvDssaY/edit