Probably about two years ago, a single monk visited our local university and created a mandala by himself over the course of a month. The result was beautiful, and I was able to attend the closing ceremony the university held. At the ceremony, visitors had the opportunity to push sand towards the middle of the mandala (including me), and then at the end, sand was put into little envelopes for the spectators, and the leftovers were poured into the nearby creek on campus as a blessing. Pretty cool!