Take three playing cards from your deck. Pick ones that you do not really care about. Two cards need to be different colored suits. For example, a three of spades, king of hearts and seven of clubs.
Fold a red card (king of hearts) and a black card (three of spades) in half, lengthwise. Fold both of the cards the opposite way as well, so you get a good crease on the cards.
Take both cards and place them back to back, so that each card face is exposed. Line the cards up so they are as even as possible.
Glue the backs of the cards to each other, but only glue half of each card together. This will leave you with one half of each card free. The fold in the cards will allow you to flip back and forth between both card faces during the trick. Let the cards dry.
Turn the glued cards over to see half of each back of each card. There will be a seam that you need to cover up with the remaining card. Line up your remaining card (seven of clubs) with the back of the glued cards. Glue the seven of clubs so that its back is exposed. This will leave your glued cards with a smooth back.
Let the glue dry before performing the trick with your blink card.