This question already has an answer here:
While building a wall along the Mexican border should not be impossible for the USA, I wonder how they could make Mexico pay for it.
One way would be to pay 50-50, but I don't see the incentive for Mexico to do this. Also, from what Trump says, it seems he wants Mexico to pay in full.
The only other way I could think of is to force Mexico to pay money by either kidnapping Mexican border guards or by blackmailing Mexico by blocking sea trade routes to Mexico using an aircraft carrier. But doing so would have an very negative impact on global image of the USA, so probably such an step won't be taken.
So what are some more appropriate options for USA?
Trump's wall plan is about how and why Trump wants to get the wall built. This one is about how he/US will make Mexico pay for it. So they are different.