An easy do-it-yourself one is to cut one large and 2 small circles out of contact paper, and stick them on your shirt in the shape of a Mickey head. Put cardboard inside so it doesn't soak through, then sponge or splatter with fabric paint around the image. Let it dry a little, peel off the contact paper, and then let it dry the rest of the way.
You have a "Mickey-relief"?, I guess is what to call it, and you can make matching, yet-a-little-different, by each family member starting with the same color shirt but using different color paint, or whatever.
Good luck, and have a great time!!!