When asked to put signs on the wall at school early last fall,
it occurred to me that you could write whatever on the computer, run it
through the copier with transparency paper and project it up there, then
paint it. It worked well. (If you can't place the projector up high
enough, you get distortions). Since then, when other department have
requested lettering, I've suggested this method, and they've been
pleased to find a way they can do this easily.