President Trump’s much-touted border wall became one step closer to reality on Tuesday.

Construction began on eight wall prototypes for the wall. U.S. Customs and Border Protection said eight wall prototypes will go up in San Diego. Eight of them will be made of concrete while the others will be made of “other material.”​

“We are committed to securing our border and that includes constructing border walls. Our multi-pronged strategy to ensure the safety and security of the American people includes barriers, infrastructure, technology and people,” said Ronald Vitiello, CBP’s acting deputy commissioner. “Moving forward with the prototypes enables us to continue to incorporate all the tools necessary to secure our border.”​