--from How 2 Zine
Sometimes I make my own envelopes to mail things in. It's a nice way to personalize whatever you're mailing. There's so much scratch paper that always gets thrown out; why not put it to some good use? Here's what I do:
Get a piece of paper (I like to use old magazine pictures, like National Geographic) and fold over the edges about 1/4"-1/2". Now, fold it up almost in half. Glue the folded edges to each other. Let it dry and you've got yourself an envelope!