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."
Note: Conni Mulligan's original post was on wikispaces, which unfortunately is no longer active. Here's the archive.org version (but some images are not archived) with some suggestions and links-> https://web.archive.org/web/20180206045744/https://conni-workshops.wikispaces.com/Green+Screen+in+Miniature
Another video to explore with some additional ideas: