Two California professors created seesaws at the United States-Mexico border wall to allow children in both countries to play with each other.

Ronald Rael, an architecture professor at the University of California, Berkeley, and Virginia San Fratello, an assistant professor at San José State University in California, came up with the idea for a “Teetertotter Wall” in 2009.

Their idea finally came to life at an event Monday in Sunland Park, New Mexico, when three bright pink seesaws or teeter-totters were added to the giant steel border wall. The contraptions, typically found at a children’s playground, stretch into Ciudad Juárez, Mexico.

“One of the most incredible experiences of my and @vasfsf’s career bringing to life the conceptual drawings of the Teetertotter Wall from 2009 in an event filled with joy, excitement, and togetherness at the borderwall,” Rael wrote on Instagram.

“The wall became a literal fulcrum for U.S.-Mexico relations and children and adults were connected in meaningful ways on both sides with the recognition that the actions that take place on one side have a direct consequence on the other side,” he wrote.

In one video posted to Rael’s Instagram page, several children are seen happily bouncing up and down on the seesaws. Another video shows people waving to children in Ciudad Juárez.

President Donald Trump, who has spent years pushing for the construction of a border wall, was cleared Friday by the Supreme Court to tap into the Defense Department’s $2.5 billion counter-drug money to build more than 100 miles of the wall.

Trump hailed the victory in a tweet, writing: “Wow! Big VICTORY on the Wall. The United States Supreme Court overturns lower court injunction, allows Southern Border Wall to proceed. Big WIN for Border Security and the Rule of Law!”