From http://www.musiciansdice.com/ : "Can be used in any number of ways – they bring the element of chance into the musical process. They're great for composing Aleatory and 12 tone-music, and as a basis for improvisation – they’re really fun in a jam session. They also make an effective study tool: they can be used as “musical flash cards” when learning harmony, and their randomness makes for fresh and challenging exercise in sight-singing and ear training. Plus, they look really cool on the coffee table, and give you a chance to throw around words like 'aleatory'."
I found these dice online and thought they would make a great gift for one of my musician friends who is always asking for a random note for him to improvise off of. I wasn't willing to cough up $20, though, nor did I think that having 12 identical dice would be necessary. So, I figured I would at least attempt to design and print something similar, and, after far more work than was probably necessary, this is what I ended up with.
I recommend printing at about half the original size.