HILLSBOROUGH, N.C. — Thirty-three years ago, Steven Burke spent nearly all of his $183 tax refund on a hand-made replica of a 16th-century mansion in Peru — a purchase that would shape his destiny.

On that day, he began collecting tiny buildings made from soap boxes or tin cans — not just houses and churches, but steel mills, diners, banks, Ferris wheels and a Gulf Oil drilling platform. He gathered miniature versions of the Chrysler Building, the Moravian church in Winston-Salem, a train station in Milwaukee and the Alamo painted red — the history of American architecture small enough for a mouse.

“I think psychosis is an unfair word,” he joked.

As this obsession grew, he and husband, Randy Campbell, packed more than 1,200 miniature structures onto every surface inside their Hillsborough home, even the bathroom. They’ve assembled the world’s largest collection of American folk art buildings — a genre Burke seems to have invented.

At 70, he has rescued and celebrated the work of a thousand mostly anonymous artists, caretaker to a little universe.

“Rendered Small,” made by N.C. State University film professor Marsha Gordon and Raleigh architect Louis Cherry, shows the sprawling collection in enough detail to see the corsets for sale through the window of the dry goods store. The 15-minute film, Gordon’s first, took four years to make.

“It really does inspire this sense of wonder,” said Gordon. “There’s something magical about taking something big and making it small. You see it and you’re like, ‘This is a museum that people happen to live in.’ “

The film grew out of the same fascination for the Hillsborough couple’s lifelong work, a love for buildings so sweeping in its scope that it includes the smelting towers of a Pennsylvania steel mill alongside the clock from Grand Central Station, so exhaustive that it fills five buildings on their lot in Hillsborough’s historic district — each one added as the collection grew larger.

The documentary isn’t a virtual tour, Gordon explained.

“That would be impossible,” she said. “Just like when you go to the Metropolitan Museum of Art, you can’t look at every piece of art. You have to make decisions.”

Burke traces his fascination with the buildings to his childhood in London, where he built toy train sets that filled the second-story drawing room of his family’s row house. More than the trains, he enjoyed lining the tracks with depots and other buildings. Campbell, who works in a book store, tends to the couple’s grounds more than its tiny houses.

Other than the first piece from Peru, the collection is entirely American, made mostly between Iowa and Pennsylvania from about 1870 to World War II. Burke notes that in that era, much more so than now, people knew how to build things.

But out of 1,200 pieces, he and Campbell know details of about 80 of them. The vast majority were crafted by unknown hands. Those few who thought to give themselves credit, such as Clyde H.S. White Sr. in 1940, did so in pencil on the underside of their work. And while Burke found some of the buildings on collecting trips, he worked full-time in the biotech field until fairly recently, and large portions of it came to his hands through eBay.

He occasionally opens his doors to admirers, with appointments made often well in advance. Busloads sometimes arrive, and Burke begins by asking them to close their eyes and picture an American folk art house. They oblige him, but they soon open their eyes and look puzzled.

They haven’t seen the Congregational church someone built with a removable roof, its interior detailed down to the open Bible on the altar. They haven’t seen the carousel someone made from lamp parts and a hubcap, its riders detailed down to the lug-nut boy eating an ice cream cone made from a screw. They don’t know yet what our ancestors did with their imagination and their free time.

So he invites them inside to see.