Here is the front of the card. His favourite character is Link from the Zelda series. I search the internet for graphics to use. I found a Hyrulian language that is used in one of the games to spell out Happy Birthday. I also placed a Tri force because it is a popular symbol in the game.
Here is the inside of the card. I coloured the images (Link; character on the left and the Master Sword with Z for Zelda on the right).
Here is the back where I sign (stamp) my name. I used yellow and green because they are Zelda/Link colours.