NOW: President Trump puts his signature on a cut of marble to commemorate the White House helipad project, then jokes about making sure everyone can see his sig

NOW: President Trump puts his signature on a cut of marble to commemorate the White House helipad project, then jokes about making sure everyone can see his signature on the new South Lawn installation. “That's pretty great... I think we should use this side. We used the wrong side. We’re flipping …