"I am honored, I'm humbled but I'm very happy," Castillo said during Wednesday night's live episode, when he was named one of 16 semifinalists, based on TV viewers' votes.
Calling Castillo an "amazing talent," judge Howard Stern said, "You really are a guy with a heart. ... America got it right." However, Stern advised Castillo to stop wearing a beret.
Castillo's breakthrough moment had been an early-round rendering of faces, a flag, soldiers and finally the Statue of Liberty with the background song of God Bless the U.S.A. The performance wowed judges Stern, Howie Mandel and Sharon Osbourne, all of whom voted to pass Castillo on to later rounds.
On Tuesday's live performance show, Castillo, 64, drew raves for his performance, which included various animals sculpted of sand.
America's Got Talent, in its seventh season, is routinely the No. 1 show in Nielsen's weekly ratings report.
Of the 12 acts that performed Tuesday, only Castillo and three others advanced to the semifinals: "earth harpist" William Close, who performed in Lexington at the 2002 ideaFestival; the performing animal troupe Olate Dogs; and mentalist Eric Dittleman.
They will compete for $1 million against the All Wheel Sports BMX stunt team, David Garibaldi and His CMYK's art performers, acrobats Donovan and Rebecca, singers Edon and Shanice and Maurice Hayes, comics Jacob Williams and Tom Cotter, pianist Tim Hockenberry, contortionists Turf, and dancers Lightwire Theater, The Scott Brothers and The Untouchables.
Castillo told the Herald-Leader on Wednesday afternoon that he "had no clue that it was going to turn into literally a worldwide phenomenon."
"It's what I call organic simplicity," Castillo said of his sand-sculpting art. "It's been an exciting adventure from the get-go. ... Like any other instrument, it requires work to make it look right and go with the music."
Castillo said his favorite piece to perform is about the Passion of the Christ. He has not yet performed that one on America's Got Talent.
Also on Wednesday's results show was a performance by the cast of the Tony Award-winning Broadway musical Once, including Ashland native and Tony-winning best actor Steve Kazee.
Although on air the show described Castillo as being from Lexington, he has lived in Richmond for several years.
NBC.com says Castillo got the idea for his sand-and-light performances when his wife sent him to the hardware store to buy mulch.
America's Got Talent will be on hiatus during the 2012 London Olympics, returning Aug. 14.
Kentucky resident Kevin Skinner, a singer and chicken farmer from Mayfield, in far Western Kentucky, won season 4 of the talent show and in 2010 released the album Long Ride.
At a press junket earlier Wednesday, America's Got Talent judge Osborne countered rumors started by a tweet she posted Tuesday on Twitter and confirmed that she will indeed return to the show next season.