There is a simple way to finance such a project as a border wall without the drama of shutting down nine agencies and departments of the federal government.
Consider the process of civil forfeiture upon seizure of international drug cartel and American street gang money, assets, and real property incident to the arrest of these principals. Thereafter, vest not only this money, but the money derived from the sale of these assets and properties, into a “dedicated fund” to pay for the wall.
The Army Corps of Engineers can then construct the thing at historically known high-volume invasion points along the southern border.