I know this project has been done countless times, but I wanted to give it a try. It's a super simple project, but you all know how I love my personalized paper goods. Though, I'm not sure it needs instructions to go with it. Simply unfold an envelope you have lying around, trace it on a magazine page, cut, fold and glue! Easy peasy! You can also use cardstock, scrapbooking paper, wallpaper, fabric or newspaper!
If you don't happen to have an envelope lying around that you can use, here are a few links to various envelope templates I found online: TEMPLATE 1 | TEMPLATE 2 | TEMPLATE 3 | TEMPLATE 4