He had an idea to make Mexico pay for it-- he would place a tax or tarrif on cars from Ford, BMW, and other large manufacturers in Mexico and the manufacturers would place pressure on Mexico to pay or they would move to the US. However there are reasons this would not work-- one being that those cars get finished in US factories with assemblies and parts from Mexico. The car manufacturers would move to other countries like Canada and close US factories. he has not said much since then. We will see.