I made this keychain out of a domino piece that I had laying around. I first colored in the circles with a paint pen, then glued the image onto the piece with a zig glue pen. For the image, I measured the front of the domino and then printed out an image in that size. Once the image was attached, I then hot glued a jump hoop (jewelry section) with a keyring through it to the piece and covered the front with mod podge. It only takes a couple of minutes for the mod podge to dry and then the image is sealed on. The image I used on this is Gir from Invader Zim. I jus think this little guy is so cute, so I thought it would make the cutest keychain. You could make this with just about any image you like.
This is also similar to the scrabble tile keychains that I have made in the past with the exception that I covered them with glossy effects and you have to wait for about 4hours for it to dry. However, that does also give them a nice coat over the top that you don't get when just using the mod podge. If you use the glossy effects, make sure to get the bubbles out before leaving it to dry, or your image will have bubbles over the top. Here are a few pictures of some of the scrabble tiles I have made for examples as well.