Doing it "tiny" : Green Screen on a small scale
Video explanation and demo, screen shots and parts lists, ideas and apps, a movie set in a pizza box:
"Traditional Green Screen MovieMaking can be overwhelming involving setup, equipment and even software. Thanks to the iPad, we can bring this editing process down to a manageable size for use in the classroom. The smaller scale also provides for quick and easy setup/breakdown of equipment and supplies when you have multiple classes or limited space in your classroom."