This is a great project for G+T students in fifth and sixth grade. Variations I have done include working individually and letting the students choose anywhere in the world they would like their country to be. The geography and climate of their portion of the earth affects the other aspects, such as history, customs, foods, etc.
This is a project that I used when I taught 7th Grade Social Studies. It was a lot of fun for the students. Teachers can assign countries based upon their particular unit of study. One of the items in the container has to be a recipe. We use these later to have a "Celebration of Culture" where we enjoy sampling food from around the world.