I watched a show one Saturday afternoon a couple of months ago, where they teamed up talented sand castle builders. They had a certain time period to build their previously agreed upon designs, all from sand-piles that had all been prepared in the same size and fashion. Every 30 minutes or so, they did a drawing with a bingo/ping-pong ball type setup. If they drew the number of the team, they then proceeded to blow their sand castle up and that team had to start all over again, using their second design. It was pretty amazing what they were doing with sand.
jag