P.S. Folks who're familiar with high school graduations won't be surprised at creative renderings on the cap and gown. That happens all the time. But know that if it crosses the line of what the school would approve, they can prevent you from going through the commencement exercise. One of my son's friends went through the effort of lots of decoration, some of which featured some fairly hostile stuff, and he turned out not being allowed to go through the ceremony, which was very disappointing for his family and friends. That's why I suggest staying within the bounds of appropriateness.