
Eight prototypes of US President Donald Trump's US-Mexico border wall have been built near San Diego.

Following up on President Donald Trump's campaign promise to build a wall along the entire 2,000-mile Mexican frontier, the Department of Homeland Security began building prototypes for the barrier along the border in San Diego and Imperial counties, as it announced in August.

The prototypes form a tightly packed row of imposing concrete and metal panels, including one with sharp metal edges on top. Another has a surface resembling an expensive brick driveway.

Companies had had until October 26 to finish the models. Crews installed a corrugated metal surface on the eighth model on a dirt lot just a few steps from homes in Tijuana, Mexico last week.

The eight prototypes for Donald Trump's proposed wall along the US-Mexico border have been completed in a border area near San Diego. Pictured side-by-side are two of the prototypes

There are six companies vying for the construction job; two companies have submit two prototypes. The companies are: Cadell Construction Company; W.G. Yates & Sons Construction Company; Fisher Sand & Gravel Company; Texas Sterling Construction Company; KWR Construction Incorporated; and ELTA North America Inc

The walls form a row and have been spaced 30 feet apart. They range in cost from $320,000 to $486,411

One stipulation is that the walls must be 'aesthetically pleasing' from the US side of the border

The models, which cost the government up to $486,000 each, have been spaced 30 feet apart.

Slopes, thickness and curves vary. One has two shades of blue with white trim. The others are gray, tan or brown - in sync with the desert.

Bidding guidelines called for the prototypes to stand between 18 and 30 feet high and be able to withstand at least an hour of punishment from a sledgehammer, pickaxe, torch, chisel or battery-operated tools.

Features also should prevent the use of climbing aids such as grappling hooks, and the segments must be 'aesthetically pleasing' when viewed from the U.S. side.

The administration hasn't said how many winners it will pick or whether Trump will weigh in himself. There is a chance that none of the prototypes will be selected.

Roy Villareal, acting chief patrol agent of the San Diego border sector, told reporters: 'It may not result in a singular winner. It may be a combination of designs being implemented.'

The eight prototypes are pictured across the border from Tijuana, Mexico. There are currently 654 miles of single-layer fence on the 1,954-mile border, plus 51 miles of double- and triple-layer fence

Four of the prototypes were made from concrete while four were made were made of material other than concrete

The six companies had had until October 26 to complete the prototypes

A woman is pictured walking in Tijuana while the prototypes loom in the distance

People pass border wall prototypes as they stand near the border with Tijuana, Mexico, on October 19

There are currently 654 miles of single-layer fence on the 1,954-mile border, plus 51 miles of double- and triple-layer fence.

Trump has asked Congress for $1.6bn to replace 14 miles of wall in San Diego and build 60 miles in Texas' Rio Grande Valley, the busiest corridor for illegal crossings. Democrats have balked at the request.

Donald Trump's promise to 'build a wall' was one of the major tenets of his political campaign. He insists that Mexico will eventually pay for the wall

The six companies vying for a chance to build the wall are: Cadell Construction Company based in Birmingham, Alabama; W.G. Yates & Sons Construction Company in Philadelphia, Mississippi; Fisher Sand & Gravel Company in Tempe, Arizona; Texas Sterling Construction Company based in Houston, Texas; KWR Construction Incorporated based in Sierra Vista, Arizona; and ELTA North America Inc, the US outlet of an Israeli defense contractor.

Cadell Construction Company and W.G. Yates & Sons Construction Company have submit two prototypes.

Contracts for the individual walls range from $320,000 to $486,411.

Of the eight contracts doled out in the Customs and Border Patrol search they awarded four to be made of concrete and four to be made of material other than concrete.

Trump's proposed border wall with Mexico has been a hard and fast campaign pledge. Building the eight prototypes has hit a milestone toward that pledge.

Trump still maintains that Mexicans will pay for the wall eventually, but says American taxpayers will front the cost until they do.