President Trump wants a wall. Democratic lawmakers don’t want to pay for it.

Here’s an elegant compromise: If Trump truly thinks building a wall is such a brilliant idea, he should pay for it himself.

I’m actually not the first to propose this. Last week, Rep. Walter B. Jones, R-N.C., suggested that our builder in chief pledge “some of his own funds” toward the wall, though Jones emphasized that a fiscally responsible approach would primarily rely on offsetting cuts to “wasteful federal spending.”

Now, saying you’re going to pay for a border wall by eliminating “wasteful federal spending” is a bit of an oxymoron.

The wall, after all, is a non-solution to a non-crisis. Or as Trump budget director and acting chief of staff Mick Mulvaney put it in a recently resurfaced 2015 interview, wall-as-immigration-policy is “absurd and almost childish.”

In recent years, we’ve had a net outflow of undocumented immigrants, with the total estimated population shrinking to a decade low in 2017. Even if you thought that dwindling number of undocumented immigrants was still a problem, note that most immigrants joining the undocumented population don’t cross the border illegally; they come in legally and overstay their visas.

Which means a wall is unlikely to do much unless it’s tall enough to stop airplanes.

There’s also the physical and legal impracticality of building a 2,000-mile wall along the southern border, where rough terrain makes construction challenging. And in Texas, most border land is privately owned, so the federal government would have to kick private citizens off their own property. There are also more effective border security technologies, such as drones, that Trump dismissed at a Wednesday Cabinet meeting as mere “bells and whistles.”

All of which is to say that spending money on a magical border wall is not a good use of billions of dollars. But if we’re gonna waste billions of dollars, at least let those billions be Trump’s.

It would be his money on the line only initially, of course. Trump has repeatedly promised that Mexico will pay us back for the costs of construction. Occasionally, he insists that Mexico has already committed this money, somehow, through his willfully confused understanding of how the still-as-yet-unratified NAFTA 2.0 will work.

If he genuinely believes the Mexican check is in the mail, he shouldn’t object to bearing the risk while we wait for it.

In the meantime, Trump can afford to float the funds himself, at least if he’s really worth as much as he claims. Plenty of shallower-pocketed Trump supporters have already pitched in with their own contributions through a GoFundMe effort to pay for the wall, which has now raised nearly $19 million.

And heaven knows he’s been bleeding taxpayers for plenty more money, between Secret Service hotel bills at Mar-a-Lago and above-market-rate rent for the military at Trump Tower. Like those GoFundMe donors, Trump could model putting America first by donating all that money back, plus anything he has collected from the political fundraisers and dubious international business coming through his hotels. (Trump pledged to donate the Trump Organization’s profits from foreign government patronage to the U.S. Treasury, but the amount of this “voluntary donation” last year — about $150,000 — was both nontransparent and almost certainly low-balled, given that we know the Saudi government alone spent about $270,000 at his D.C. hotel over just the several months around his inauguration.)

Trump could probably claim a charitable deduction for the cost of the wall, even if he paid for it directly rather than giving funds to Treasury first.

And even if he chooses not to categorize the construction project as charitable — sometimes he claims closing the border is a “profit-making operation,” after all — perhaps he’ll see this as a great branding opportunity.

He could plaster his name across 2,000 miles of borderland, maybe even make it visible from space. After he’s out of office, if the government has eminent-domained all that private Texas property to Trump personally, perhaps he could turn the area into a massive Trump theme park complete with bumper cars and baby cages.

But the best possible outcome might be this: If Trump believes that he — rather than the taxpaying public — is on the hook for construction costs, he might just declare the thing already built. He can instruct Fox News to air some B-roll of the Great Wall of China and hope his supporters don’t notice the difference, and we can all, at long last, move on to the next fake crisis.

Catherine Rampell’s email address is crampell@washpost.com.