Since no one has given you any ideas yet, I've got a couple that you might consider. The first is to go to any Home Depot, and go to their paint chip section. There you will find that Behr paint has paint colours with a Disney theme. The paint chips are shaped like Mickey Mouse heads. Grab a pile of different colours. Then go to your local craft store and pick up a large piece of poster board. Cut out the Mickey Mouse heads, then number each one individually for the amount of days you want the count down calendar. Then in the middle of the poster board write "DIsney vacation" or basically whatever you want to say, then get a glue stick and glue all the mickey mouse heads onto the poster board around what you have written. The idea is each the child can take off one of the numbered Mickey Mouse heads till there is none left.