Ever since Donald J. Trump announced his plans to build a wall at the border, pundits and voters have been debating how it would work. Now a pair of artists have offered an example: They have built a wall — or the start of one, anyway — near the edge of Jacumba Hot Springs, Calif., a border town about 70 miles southeast of San Diego.

“It took about 52 cinder blocks,” David Gleeson, one of the artists, said by phone on Wednesday afternoon, shortly after he and his partner, Mary Mihelic, erected their version of Mr. Trump’s wall. It stands 20 yards from the actual United States-Mexico border, which already has a fence. Covered on one side by a large campaign ad for Mr. Trump, the presumptive Republican nominee, and studded with wilting fruit, flowers, cleaning items and hardware, their wall was meant to symbolize, Mr. Gleeson said, the economic effects that curtailing immigration and closing borders would have on agriculture, industry and domestic life.

The structure is abbreviated and remote; Ms. Mihelic hopes that other artists will add to it. “Art has to be present more in these disruptive and contentious moments,” Mr. Gleeson said.

Given Mr. Trump’s promise that he would get Mexico to the pay for the wall, Mr. Gleeson and Ms. Mihelic sent an itemized bill to Enrique Peña Nieto, the president of Mexico: $14,635.42 for their materials and labor. (They had some fun with the accounting, they said, in homage to Mr. Trump.) The receiving address for payment is Trump Tower.