If you're a poor grad student like myself, you know owning fancy tools like a light box is a luxury. Hopefully your university should have one or two for use (mine does), but if you are at home rendering and realize you need a duplicate character, here is my hack for a light box.
Make sure your original and "new copy" are lined up. Tape the corners to the window very lightly. Trace away!
Needless to say, make sure it's light outside. Don't try this at night unless you live in my apartment with a street lamp right outside the window. Even then, don't do it at night. Daytime tracing for best results.
This really doesn't replace a light box or scanning your design and printing another. But, if you need it on paper that doesn't work in your printer, this will work in a pinch.
If you're exploring designing a show but don't want to sketch out all the characters, check out the article: Interpreting Design Without Drawing.