The idea that would consume two years of his life and drain $20,000 from his bank account, the obsession that turned his garage into a jaw-dropping shrine for his favorite football team, came to him in the middle of the night.

Don Martini had been searching for a new project. He had built kayaks and gazebos and furniture in his Blairstown workshop, turned his backyard into a village with an elevated rail for model trains, a working windmill and a lighthouse. He needed something else. Something bigger.

“I’m going to build Giants Stadium,” he declared one morning, and his wife Janice replied the way you’d expect to a statement like that.

“You’re crazy,” she said.

But not even she could have known just how crazy. There is a line fans cross between liking a team and taking it to another level. Many tailgate before home games, but only a few do it with a professional grill alongside a Winnebago painted in team colors. Most know the names of their favorite players, but only a few know their birth dates, too.

Some might have a photo of Giants Stadium in their garage. Only one has the actual thing in his — or at least as close as there is in the world right now.

Nothing prepares you when you walk through the door, because the words “model” and “replica” are insufficient to describe what Martini has constructed. It is 20 feet long and 17 feet wide. It was built with an attention to detail that, truth be told, the original architects never had.

Giants Stadium was deemed obsolete soon after it opened. It was torn down in 2010 after just 34 years of service, and in the years since, few have mourned its demolition. Martini did. He loved it enough to spend eight hours a day for nearly two full years rebuilding it, selling his antique car to clear the space.

He had no plans. Just a vision.

“Have you seen the movie Mozart’s Amadeus?” Martini said. “Well, in the movie, the emperor commissions him to write an opera. In the process of writing it, the emperor would say, ‘I want to see the first scene.’ Mozart told him, ‘I don’t have anything to show you. It’s all right here in my noodle.’ ”

He points to his head — which, of course, is covered with a Giants cap.

“That’s the same way it was with this.”

LOVES TO CREATE

But Mozart had a clear reason for his life’s work. He was making music for the world. Martini built his stadium in a garage behind his family’s bagel store, in an isolated place where precious few have seen it.

So the first question is obvious: Why?

How does a 75-year-old grandfather and retired school teacher suddenly wake up and decide he’ll dedicate countless hours leaning over a table saw to cut 65,000 red-and-blue seats?

“I know, there should be 80,000,” he said, almost apologetically. “But there’s only so much room inside.”

The answer has as much to do with loving the Giants as it does with loving to build. Martini invented and patented a universal assembly jig for cabinet making that allowed him to retire in his early 50s, and in the two and a half decades since, he has spent his days and nights creating.

He took the plans for a 14-inch model train and turned it into a 17-foot piece of art that sits on a shelf in his living room. He built the massive TV cabinet a few yards away, and the dining room chairs on the other side of the room, and the sprawling deck that overlooks the fields for North Warren Regional High.

Each project became a little more challenging. It wasn’t enough to have one waterfall in his backyard village. He has nine. One birdhouse outside his gazebo, the one with stained glass windows in the roof, became five. Why would he build a remote control boat his grandkids could play with when he could build one big enough for them to ride in?

He considered building a 40-foot replica of the Empire State Building but gave up when he found out all the permits he needed. But even that seemed too mundane — other people have duplicated the world’s great buildings in all kinds of materials. He wanted something special.

His favorite football team was in the process of opening its new stadium when he decided to pay homage to its old one.

GETTING STARTED

The first challenge: Where to begin? Martini had photos and general specs from the internet but not much else. He spent weeks, through trial and error, getting the pitch of the three levels of the stadium just right. Then he had to figure out how to make all those seats.

He considered making them one at a time, but that could take years itself. He decided to take 8-foot-long pieces of a special moulding and make a small cut with his table saw every three-quarters of an inch.

“It was tedious, but I knew I had to do 100 a day or I’d never get done,” he said. “I couldn’t work on those all day because I’d go cuckoo.”

Each one of those distinctive eight coils, the ones that were crowded with foot traffic after games and smokers during them, took a week to craft with plywood, plaster and other supplies.

Those coils, as diehard fans remember, were separated with three escalators that went to the different levels. Martini had to order the Plexiglas cover for them, just 1/32nd of an inch thick, from a company in Arkansas.

That was always the challenge: Finding just the right pieces. He needed 235 tiny 5-watt halogen bulbs for the light stanchions, at $1.96, that he would fasten into place with special hose washers. The salesman at the lighting store had never received such a weird order.

“What the heck do you need these for?” he had to ask.

“I’m building Giants Stadium.”

“Life size?” the man replied.

“I’m crazy, but not that crazy.”

He installed two small TVs, one in each end zone — one plays Super Bowl XLII on an endless loop, the other shows the NFC Championship Game victory from that season. He bent strips of metal used on electric fences (paper clips or aluminum didn’t work) for handrails.

He got help from a computer savvy friend to make a glossy printout for the field, then added the benches and tiny orange Gatorade jugs. He even added sponsor billboards, and when the owner at Blue Ridge Lumber saw his, he was so happy that he gave Martini $200 in store credit.

But he didn’t stop at building a stadium. Martini painted the walls of the garage blue and hung autographed photos from each Super Bowl team. He built something he named “Giants Stadium Trolley Station,” with a working train and elevators, that would have alleviated hundreds of traffic jams had the Meadowlands planners thought of the same thing.

He added five Blue Angel fighter jets flying overhead, three cookie jars filled with blue-and-white M&Ms for the kids, a wall-sized photo of the New York skyline, even a stadium timeline and history lesson.

A fan could spend an hour in the room and not notice everything. But how would fans ever see it?

Martini didn’t start this project as some sort of football “Field of Dreams.” His friends have encouraged him to charge a few bucks for visitors, but that idea never appealed to him. He built it for himself.

Now and then, a Giants fan will enter his bagel shop and Martini will tell him, “I have something you’ll want to see.” The fan almost always protests — too busy, in a hurry, whatever — but Martini insists.

“And then they walk through the door,” he said, “and without fail, they say, ‘Hoool-eee …’ ”

His son, Don G., has encouraged him to give it to the Giants, maybe in exchange for season tickets. Team spokesman Pat Hanlon called it “a wonderful tribute to a building that housed many wonderful memories” and wanted to discuss logistical issues before accepting or declining the gift.

Even if the Giants agree to display it, Martini has mixed emotions about parting with his creation. He worries about damaging it during transport and enjoys coming into his garage to spend time with his Giants Stadium — the only one like it in the world. For now, at least.

“Maybe,” he said, “I could build another one.”

Steve Politi: spoliti@starledger.com; twitter.com/StevePoliti