Can an amateur craftsman, on the floor of his unheated home, duplicate a world-famous violin? That’s the central question of the ‘Strad Style’ doc

He started playing at age 2½ and had his debut with the Philadelphia Orchestra when he was 10. So when film director Stefan Avalos says “I’ve never not known the violin,” he is not being hyperbolic.

But even Avalos had never met anyone like Danny Houck, the violin-obsessed subject of his irresistible, way-stranger-than-fiction documentary “Strad Style,” which screened this week at Sundance’s cross-town rival, Slamdance.

An eccentric loner living on next to no money in a rundown farmhouse in little-known Laurelville, Ohio, Houck lives and breathes the violin. “His knowledge is encyclopedic, he will tell you things you never knew,” reports Avalos. “He is absolutely obsessed and immersed in the thing.”

More than that, Houck somehow contrives to build violins as well. And when he agreed to make an exact copy of Guarneri’s Il Cannone (the great Paganini’s instrument and one of the most famous violins ever made) for a rising European star, a personal and professional journey that almost defies belief began.

Avalos, who eventually transferred allegiance from music to movies, was contemplating something else entirely when Houck crossed his path. “I had been working for two years on a wide-ranging documentary about the obsession people had with the great violins, about the makers, the players, the collectors and the thieves,” he says.

“I heard through the grapevine, from a player at the Columbus Symphony,” Avalos continues, “about a guy who lived in the middle of nowhere and was really obsessed with making violins. I thought he would make an amusing five-minute bit in my film.”

But once the director met Houck, who has a tattoo of great violinist Jascha Heifetz on one of his arms and the great violin maker Stradivari on his calf, everything changed.

“Within half an hour I had a whole different movie in mind,” Avalos says. “For a documentary filmmaker, Danny was a dream subject. He was quirky, intelligent, great on camera, the whole works.”

Avalos set aside two years of interview footage and decided on another, more observational tack here. “I really tried to channel Frederick Wiseman and the Maysles brothers, to provide a slice of life.”

Houck, who is bipolar, had played the violin as a child and had decided to make them because it was the only way he could afford to own one. “He used the Internet, read books before that,” Avalos says. “He had raw, untrained talent, a real gift, but he was completely self-taught.”

Soon after Avalos had made the decision to change the focus of his film, Houck told him that, via Facebook, he’d made friends with a rising European violin star named Razvan Stoica. Says Avalos, “Razvan was obsessed with Paganini and told Danny, ‘My dream violin would be Il Cannone.’ When Danny told me he had offered to make Razvan a copy, that’s when bells went off.”

Plans and diagrams of Il Cannone exist, but Houck had never seen the actual violin. “That was pretty audacious, like saying you can make a NASCAR racing car without having seen an engine block.”

Plus Houck’s work spaces, which sometimes included spreading out on the floor of his unheated house, were not exactly pristine, “so it was like trying to discover a new element in your kitchen.”

Even more unnerving, when Los Angeles-based Avalos decided to devote himself to this project, coming out to Ohio a week or two at a time over a nine-month period, he’d never had a chance to hear how one of Houck’s earlier instruments actually sounded.

“I’d call my girlfriend and she’d say, ‘Have you played one yet?’” the filmmaker remembers. “Finally I got the chance and the tone was just gorgeous. I called and told her, ‘I played one, it’s good!’ I didn’t know whether he was delusional or not. It was a big relief.”

But could Houck pull off Il Cannone in time for the European concert Stoica needed it for? That was an entirely different question, with the answer in doubt even within the last 24 hours of the deadline.

Not in doubt, Avalos reports, was the audience response at the first Slamdance screening on Saturday. “It was beyond anything I could have expected,” he says. “They applauded all through the end credits and then gave it a standing ovation.”

As for the director himself, “I’ve watched it about 150 times and I still have an emotional reaction. That’s not supposed to happen, a magician is not supposed to be wowed by his own tricks. It has absolutely exceeded my expectations.”