President-elect Donald Trump has already built a wall - not on the border with Mexico, but on the border of his exclusive golf course in northeastern Scotland, blocking the sea view of local residents who refused to sell their homes.

And then he sent them the bill.

David and Moira Milne had already been threatened with legal action by Mr. Trump’s lawyers, who claimed a corner of their garage belonged to him, when they came home from work one day to find his staff building a fence around their garden. Two rows of grown trees went up next, blocking the view. Their water and electricity lines were temporarily cut. And then a bill for about $3,500 arrived in the mail, which, Mr. Milne said, went straight into the trash.

"You watch, Mexico won’t pay either,” said Mr. Milne, a health and safety consultant and part-time novelist, referring to Mr. Trump’s campaign promise to build a “beautiful, impenetrable wall” along the border and force the Mexicans to pay for it.

The Milnes now fly a Mexican flag from their hilltop house, a former Coast Guard station that overlooks the clubhouse of Mr. Trump’s Trump International Golf Links, whenever he visits.

So do Susan and John Munro, who also refused to sell up and now face an almost 15-foot-high earthen wall built by Mr. Trump’s people on 2 sides of their property.

Michael Forbes, a quarry worker whose home sits on the opposite side of the Trump property, added a second flag - “Hillary for President” - perhaps because Mr. Trump publicly accused him of living “like a pig” and called him a “disgrace” for not selling his “disgusting” and “slumlike” home.

In the 10 years since Mr. Trump first visited, vowing to build “the world’s greatest golf course” on an environmentally protected site featuring 4,000-year-old sand dunes, they have seen him lash out at anyone standing in his way. They say they watched him win public support for his golf course with grand promises, then watched him break them one by one.

A promised $1.25 billion investment has shrunk to what his opponents say is at most $50 million. Six thousand jobs have dwindled to 95. Two golf courses to one. An 8-story 450-room luxury hotel never materialized, nor did 950 time-share apartments. Instead, an existing manor house was converted into a 16-room boutique hotel. Trump International Golf Links, which opened in 2012, lost $1.36 million last year, according to public accounts.