President Donald Trump has a lot of views on what his long-desired border wall should look like, The Washington Post reports.

He has instructed aides and engineers to paint the bollards that make up the wall black to make them too hot to climb in the summer, make them pointed so climbers risk injury, and narrow the openings in between gates, The Post reported Thursday.

He is "micromanaging the project down to the smallest design details," The Post said, adding that he sometimes woke up officials early in the morning to discuss his ideas.

Trump's desired border wall has proved to be expensive. Democratic lawmakers have been fighting to limit the amount of military money Trump is spending on the wall.

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President Donald Trump is "micromanaging" plans for his long-desired border wall, including by instructing engineers to paint the bollards that make up the wall black so they absorb heat and to install pointed tips on the wall so people would risk injury by trying to climb it, The Washington Post reports.

He wants to paint the wall's bollards "flat black" because the dark color absorbs heat and would be too hot to scale in the summer, he recently told White House aides, Department of Homeland Security officials, and military engineers, The Post reported on Thursday.

The president has also called for the tips of the bollards to be pointed and not round, The Post said, adding that he had described "in graphic terms the potential injuries that border crossers might receive."

People on the Mexico side of the border wall near San Diego in June 2018. Adrees Latif/REUTERS

'Micromanaging the project down to the smallest design details'

Trump has also complained that the current prototype for the wall has too many gates for people to pass through and called for those openings to be narrowed, The Post reported.

He also wants the structure to be "physically imposing but also aesthetically pleasing," The Post said.

He is "micromanaging the project down to the smallest design details" and would even wake Kirstjen Nielsen, then the Homeland Security secretary, in the early morning to discuss his plans, The Post reported.

The Post added, however, that Trump had repeatedly changed his instructions and suggestions.

Business Insider has contacted the Department of Homeland Security for comment.

Trump at a rally in El Paso, Texas, in February. A border wall has been a key talking point for him and his supporters. (Photo by Joe Raedle/Getty Images

'A personal slush fund to fulfill a campaign promise'

Trump's desired border wall — which has been a major policy and talking point since his 2016 presidential campaign — has come with a steep cost, both financially and politically.

Since the president declared a national emergency in February to divert military funds to build his wall, the Department of Defense has redirected billions of dollars from operations, including counternarcotics and ballistic missile and surveillance plane systems, to fund the project.

High-ranking House Democrats are fighting to cap the amount of Pentagon money the Trump administration can take for the project.

Supporters chanting "build that wall" at a rally for Trump, then a Republican presidential candidate, in Rothschild, Wisconsin, in April 2016. Associated Press/Charles Rex Arbogast

Rep. John Garamendi, the Democratic chairman of the House Armed Services Subcommittee on Readiness, suggested in a Thursday statement cited by Defense News that the president was using the military construction budget "and other critical projects as a personal slush fund to fulfill a campaign promise."

Garamendi, whose subcommittee oversees military construction, presented a bill Wednesday that would cap military spending at $250 million per national emergency, Defense News reported.

From late December to early January, the US government partially shut down for a record 35 days when Trump rejected Congress' short-term funding extension because it did not include money for his border wall.