Here are a couple of Rhode Island sand castles from Crescent Beach (one made by inverting buckets, one made with the drip technique I favored as a kid) and an elaborate castle that Suzanne photographed when she was in Copenhagen earlier this month.
This website promises to teach you how to make the perfect sand castle. It involves keeping the sand moist at all times so the castle doesn’t crumble.
Suzanne's Mom's Blog 