Border wall prototype construction enters its final days along the United States’ Southwest border in San Diego, CA.

President Donald Trump promised to build a wall on the U.S.-Mexico border. Prototype construction began last month, with crews given 30 days to complete their models.

Watch these latest construction videos from U.S. Customs and Border Protection:

Taken October 8, 2017

Six companies were selected to build eight prototypes.

Taken October 7, 2017

Four models are made of concrete and four are made from other materials.

Taken October 6, 2017

Taken October 4, 2017

The construction site is located near the Otay Mesa Port of Entry.

Taken October 3, 2017

Once complete, the government will run a series of tests on each prototype, checking for anti-climbing, anti-breaching, and anti-digging capabilities, among other things.

Taken October 2, 2016

Amanda House is Breitbart News’ Deputy Political Editor. You can follow her on Twitter at @AmandaLeeHouse.