See the Eight Completed Prototypes of Donald Trump's Border Wall

Following up on President Donald Trump's campaign promise to build a wall along the US-Mexico border, eight prototypes of the barrier have been erected near San Diego.

The models, which all stand between 18 and 30 feet high, are an initial step to set Trump's nearly 2,000-mile border security plan into motion, which is now estimated to cost $1.6 billion.

The prototypes were constructed by six firms chosen by U.S. Customs and Border Protection (CBP) in September for a total cost of $20 million.

"We want a better barrier. One that is hard to scale, hard to penetrate and hard to tunnel under," San Diego Border Patrol chief Roy Villareal told reporters, TIME writes.

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Each of the wall prototypes boasts unique features, varying in slope, thickness and aesthetics. Four of the models are made of concrete and another four of concrete and steel reinforcements, NPR reports, and one is also topped with spikes as an additional safety measure. Most designs mimic the desert's gray, tan or brown colors, but one mocks the style of a brick driveway and another has two shades of blue as a contrast to the others.

The walls must be able to withstand at least an hour of destruction attempt from a sledgehammer, torch, chisel or other craftsman tools, the Daily Mail reports, citing bidding guidelines. They must also prevent the use of grappling hooks or climbing tools.

As the designs are tested, one or more prototypes may be selected as the winner, though there is a chance that none will be chosen as the construction model for the proposed border wall.

CBP has not announced whether Trump will weigh in on the construction decision, but the progress led him to share a video montage on Twitter on Oct. 17.

BORDER WALL prototypes underway! pic.twitter.com/arFNO80zmO

— Donald J. Trump (@realDonaldTrump) October 17, 2017

Trump has asked Congress for $1.6 billion to replace 14 miles of current border protection structures in San Diego and build 60 miles in Texas' Rio Grande Valley, where most illegal crossings occur. Democrats have responded by demanding that any border wall funding be removed from DACA reformation plans, an Obama-administration plan to protect nearly 800,000 immigrants were entered the U.S. as kids.

Though funding is a looming issue, the state of California is also working to block the construction of a border wall along its territory. The state filed a lawsuit in a San Diego court in September to block the wall's construction.

Still, the prototypes' erection is a move toward Trump's promise to build the wall, securing the nation's boarder from illegal immigrants. Though he insists that Mexico will fund the wall in time, his plan notes that American taxpayers will pay for it until they agree.

Photo credit: Getty / Guillermo Arias / Contributor