"Randall is the best. He's a perfectionist," said Bill Hylen, an antiques dealer who specializes in stained glass.
Claggett also picked a great time and place to be in the business, Hylen said. In the late 19th century, when stained glass was at its peak, the Northeast was home to the best glassmakers and the wealthiest clients.
Now, the East Coast churches and estates that splurged on stained glass are "100 years old, 150 years old, and they need work," Hylen said.
This year has been particularly fruitful for Claggett, who is finishing an overhaul of the 20-foot-wide rose mosaic ceiling at the Elkins Estate and who has other projects in Manayunk and York.
In an industry laced with opulence, Claggett has collected an arsenal of anecdotes over the years.
Places like the Elkins Estate, he said, "were just summer homes. They're not even for these people, they're for guests and parties."
The basement of the Glen Foerd mansion in Philadelphia was a gentleman's billiard room, he said, and "the walls still reek of booze and cigars."
Another cringe-worthy tale: the late 19th-century glass door panel that was lying undetected on a basement floor. "They stepped on it, and just craaaaack."
Claggett was able to save the top panel, featuring an ethereal songbird, but had to recreate the central element - a hand-painted Renaissance-style portrait of a woman in ornate robes, with flowing hair and delicate facial features.
Then there was the family that took a 1575 window panel from a German cathedral and displayed it on an easel. Naturally, the cat knocked it over.
Like many old European panels, its details are so small and intricate "probably no one ever saw them," Claggett said.
The panel, little more than a foot square, is crammed with two battle scenes and a castle where two men walk over a bridge. The figures are so small you can't see them until your nose hits the glass.
Straining his eyes on the tiny details is one of the perils of the job - along with high scaffolds and sharp edges. "I have Band-Aids in my pocket all the time," said Claggett, a soft-spoken artist who works in jeans and flannel shirts.
But the hardest thing, he said, is weathering the slow years. "Some studios always seem to have work. For me, it's been feast or famine."
After a few years of famine during the recession, when churches and nonprofits put off repairs and few people wanted custom designs for their homes and offices, Claggett's business is feasting again.
Castle Studios has lined up $225,000 in billings this year, he said.
Joe Beyer, who runs a larger Philadelphia studio where Claggett once worked, said the stained-glass industry was hard to crack.
"Many have tried and most have failed," Beyer said.
In his studio last week, to a sound track of soft reggae music, Claggett painted the final pieces of the gilded-vine ring that surrounds the oval rose at the Elkins Estate.
He painted from memory, dabbing and swiping the brush to create highlights and depth. Unlike on canvas, where the artist builds the image up with paint, glasswork is done by taking paint away to let light pass through.
Claggett, who uses subcontractors for large projects, was also cleaning and securing the fleur-de-lis etched ceiling in the room that used to be Mr. Elkins' art gallery. In recent years, it was rented for parties, and some panels had dislodged and were dangerously close to falling, Claggett said.
"You have full-on wedding bands jamming up there, and the pieces are just jumping, jumping, jumping around," he said. "From 30 feet, that's going to hurt."
He also tracked down a replacement for the discontinued rose-colored glass that makes up the bulk of the ceiling.
Glassmakers, he said, are always introducing new lines, colors, and textures to meet trends. "It's like cars, you know," he said. "They'll make a Toyota Corolla for 20 years and then stop."
The color he found is so close no amateur could detect the difference. But to Claggett's eye, it's still "not quite right."
Sister Anne Lythgoe, whose Catholic order owns the Elkins Estate and is preparing to sell it, said the minute details were taking longer than expected, but they "make a world of difference."
"He's a craftsman of the highest caliber," she said. "I didn't want to rush him."