DOWNERS GROVE, Ill. — On a Christmas long ago, Ken Hammer slipped a gift under the family tree he felt sure would delight his two young children: a German-made electric train set, complete with a replica 1930s steam engine.

The kids weren't thrilled. But Dad was.

"It rekindled a passion in me. It all blossomed from there," said Hammer, a 58-year-old financial adviser in Chicago.

Eighteen years later, that set has grown to 500 feet of track, 200 cars and 25 engines, some of which whistled and chugged around a living room Christmas tree recently at Hammer's Victorian home.

A legion of aficionados across the country — usually men near or in retirement — devote their free time to buying, maintaining and playing with expensive and elaborate toy trains in their basements, garages or backyards.

With some layouts costing tens of thousands of dollars, a prerequisite for toy-train junkies is plenty of cash. An engine like the brass-bodied Garratt MS0072 LS steamer, for instance, runs about $4,500.

"It's a rich man's toy," said Elaine Silets, owner of Huff & Puff Industries, which designs and installs elaborate track layouts. Her Barrington-based company's layouts start at $25,000 "and go skyward from there," she said.

It was only after entering middle age, well into successful careers, that many devotees of high-end trains were able to indulge their passion.

"Once your family is taken care of, your children are raised, you can do these kinds of things," said Fred Haverkamp, a 58-year-old owner of a Chicago metals factory. "I can afford to fulfill these fantasies now."

There's a strong nostalgic streak in most model railroaders. Many had toy trains as kids, before the age of video games and computers, when a Lionel locomotive was a child's dream Christmas gift.

For many older men, "a lot of it is returning to your childhood and returning to your youth," said Hammer, who got a train set for Christmas as a boy.

Most ardent hobbyists also are old enough to remember the heyday of the railways. Haverkamp recalls sitting by the railroad tracks for hours as a boy, watching trains whoosh past.

"When it went by, a steam train sounded like a tornado," he said. "The vibration going through you was indescribable. It was a beautiful sight."

He has spent more than $50,000 constructing a quarter-acre layout in his backyard, with 2,500 feet of track that winds and crisscrosses through miniature towns, tunnels and mountains fashioned from stone blocks. Haverkamp built much of the layout, including the bridges, himself, often using equipment at his factory.

Some aficionados obsess over details, adding miniature human figures in period clothing or fully furnished houses, accurate down to toilets smaller than a pencil eraser.

Many are such perfectionists that even a derailment is seen as a mark of dishonor, said Don Miller, a 76-year-old retired business executive with an outdoor set at his home on Chicago's North Shore.

"I get a kick out of the derailings, the crashes, the imperfections," he said. "But I'm the exception among these guys."

But as younger generations turn to video games and other electronic toys, the future of the hobby is unclear. The average age of devotees was about 30 in the 1970s, around 40 in the 1980s and 50-plus in the 1990s, according Sam Posey's book "Playing With Trains."

A lot of kids "find it boring," Hammer said. "It's not action-packed all the time."

In fact, when it comes to holiday gifts, the tables are turned at the Hammer household.

It's his kids who buy him toy trains for Christmas.