This isn't incredibly new or exciting, but a lot of people don't seem to realize you can do this. I got a kick. I've been doing this for a few weeks now, sticking the contents from the main envelope and the envelope itself in the reply envelope and mailing it off. It's incredibly simple and for some reason very satisfying. I'm going to go price some wood shims soon and see if they are actually $1.50 for 12 like the video claims, and if so I'll probably invest in some of those as well.