To build something worthwhile, you’ll need a few essentials: buckets, plenty of manpower, and the calming white noise of lapping waves. If the ocean is nowhere in sight, play it from your phone. In Zoe Hawk’s nostalgia-dipped canvas, the resolve of a high summer day takes shape, when the greatest problem was how best to keep a sandcastle from falling. Send it to your girl group and see if, this summer, you can find a weekend for the playful excursions of old times.