This pattern is worked flat to desired length, then the cast on and bound off edges are sewn together to make a loop. Add a twist if you like for a faux mobius, or leave it flat. This size should be suitable for children and adults.

This pattern was on About.com (which no longer exists) and has been deleted from their site, but for now it can still be found on the Internet Archive. They redirect and delete pages a lot so you may want to download/print to save.