It isn't impromptu you need a setup but it's quick: 2min and you can make the trick twice.
It's easy and Dan give tips for be clean.
I prepare a routine who combinate Angle zero and Laced, it's difficult but possible.
No no first angle zero: the corner dissapear, make it appear, and after that i saw to the public "i've make dissapear and traveller a little corner now do the same with the card", i give the corner to the spectator and make appear the card to my shoelace, compare the card and the corner, is the same =)