Nothing!
Cook it hot on the spot.
My business card is empty.
I ask the ones who receive it to write down HUMADNESS and,depending on the occasion, my phone or e-mail or whatever needed.
Then I fill up some ornament-details.
We spent 45'' to fill up my business card. Now it's worth more than any other business card you've ever received just because you had to invest 15 times more time than usual.
