Participants compete in several categories and can create anything they want — animals, intricate castles, boats, even people.
After Bob Hope died in 2003, one team won a prize for a sand sculpture of his face, Lesley said, adding, "It was really unique, and it was well done."
Teams of up to eight contestants will have three hours and a 15-by-15-foot square to build a masterpiece. Structures must be made of sand and natural materials like shells or seaweed, and creators can use hand tools, buckets, a ladder and a wheelbarrow.
Last year, about 33 people participated, and Lesley said he expects 30 to 40 castle builders on Sunday, with family groups and organizations welcomed.
"It's a really great event for a family. They work together, and it's fun," Lesley said.
Each team will get T-shirts and four round-trip tickets to Catalina.
Lesley said participants should arrive at 10 a.m., with castle building from 11 a.m. to 2 p.m., followed by an awards ceremony.
The event will be held at Corona del Mar State Beach at Ocean Boulevard and Marguerite Avenue.