The Berghausen set is a sight to behold: on a stand measuring 3.5m by 2.5m, miniature tracks wind round lush Bavarian mountains and pass through floodlit stations filled with tiny waiting passengers.
"I love detail, and if you are going to make something, you have got to make it real," Mr Kopppe said.
He listed the set on Trademe last week with a reserve of $7500, and was overwhelmed by the response - especially after the website placed the set on its "Cool Auctions" page.
"I was absolutely amazed. We got around 9000 hits, and the feedback from friends who were upset for me was just wonderful," he said.
One message left on the listing by a Trademe user read: "I'm so sorry to see you are unwell. I love your train set, you have done a really beautiful job. Love to the healthy parts of you."
It sold on Monday to a buyer from Blenheim, and although Mr Koppe declined to name the final sale price, he said he was pleased.
"And it's not about the money anyway. It's passing on a legacy."
Some of the sale proceeds will go towards a more manageable, smaller model railway, and Mr Koppe said he will also be making a number of charitable donations.
A lay preacher at Trinity Ngongotaha, Mr Koppe said the Berghausen set had made sure his time was "well divided between heaven and earth". He didn't regret any time (or money) spent on the set, and praised the benefits of having a hobby.
"You need one to enjoy yourself and mentally release yourself," he said. "You never get back what you put into it, that's it, it's gone. But it's been my pride and joy for a long time.
"I'm sad to see it go, but most things come to an end. I am very proud of what I have done."
