The long line of visitors queuing to see Roslyn Reynolds' miniature model railway set in the Blue Mountains is a reassuring sign that other people share in her fascination of trains.

The 72-year-old's interest in railways began in the 1950s when her family moved to Saint Marys in Sydney's western suburbs.

Nearby was the AE Goodwin engineering firm where locomotives were manufactured.

"It's a passion. I've been interested since I was four years old, so it's something that I've had all my life," Ms Reynolds said.

The miniature train set is modelled on the popular H0 gauge, which is 1:87 scale. ( ABC Central West: Luke Wong )

Roslyn Reynolds' miniature railway set is thought to be one of the largest private collections in Australia. ( ABC Central West: Luke Wong )

It's a hobby she would later share with her husband, Keith, when they met through the Blacktown Model Railway Club.

In 2000, the couple began building their dream display within a large shed behind their home in the Blue Mountains village of Valley Heights.

Ms Reynolds, a former retail employee, found escaping to the miniature world was her daily stress release after a hard day's work.

"It's so relaxing," she said.

Celebrity visit highlight

Ms Reynolds said a highlight for the couple was when television gardening presenter Don Burke and his crew came to visit.

"They sent a photographer up to start with to take some photos, but the photographs didn't do the trains justice," she said.

"They walked in the door and got the shock of their lives."

There's a lot to keep an eye on during open days. ( ABC Central West: Luke Wong )

It takes at least nine volunteers to help with the running of the train set during open days. ( ABC Central West: Luke Wong )

After Keith died in 2009, Ms Reynolds continued to add to the collection and opened the display in the shed for public viewing twice a year.

Almost two decades of construction, along with countless additions to the track, she estimates the collection is now worth $250,000.

Volunteers all aboard

Throughout the open days, volunteers from the Blue Mountains and Nepean Christian Railway Group and the Valley Heights Locomotive Depot Heritage Museum help keep the trains running to schedule.

"It takes nine people to just to operate it because of its size," volunteer Lee Hawkins said.

"That we know of, it's one of the largest in Australia."

Mr Hawkins said his enthusiasm for trains was fuelled during his time as a trainee guard at the Zig Zag Heritage Railway near Lithgow.

He said Ms Reynolds' model train set captured a slice of Australia's transport history for younger generations.

"It shows kids who don't see big steam trains what it was like back in the '60s, '70s when steam was present."

The miniature model train set captures slices of rail transport history for younger generations. ( ABC Central West: Luke Wong )

Roslyn Reynolds has been a lifelong railway enthusiast. ( ABC Central West: Luke Wong )

All for the community

From the gold-coin entry fee collected from visitors, Ms Reynolds has donated thousands of dollars to hospital chaplaincies in Penrith, Springwood and Katoomba.

She also volunteers five days a week at the Valley Heights Railway Museum, spending much of the time maintaining the gardens that she and Keith helped build.

Ms Reynolds said sharing the joy of railways with hundreds of visitors each year was something her late husband would have been proud of.

"He would love it. He was train-mad as well."