LOS ANGELES (AP) — As a billionaire developer, Donald Trump built casinos, luxe condo towers and lush golf courses. [...] as president, Trump aims to develop perhaps his most ambitious and surely his most contentious project yet: A wall along the nearly 2,000-mile U.S.-Mexico border. Ultimately, though, experts say the project, if built, could deliver a windfall for some large construction companies and their suppliers. Engineering and infrastructure companies that have worked on previous government projects could capture a chunk of the multibillion-dollar work. [...] the project would likely also be stymied by the struggles that have beset the industry in recent years, notably a shortage of skilled labor and rising materials costs. Some of the big companies include a subsidiary of the construction and engineering firm Parsons Corp.