Still, I don't always have a mailer lying around, and besides, the ones I use are just the usual business yellow type. How much more awesome to send bright, colorful ones whenever it's appropriate to be a bit less formal. And they can be bought. This one is available from Etsy:
website with all the instructions you need to create your own one of a kind decorative bubble mailers. She used scrapbook paper, but another instructional mentioned card stock or pretty (I'm assuming heavier) paper as options.
And, as usual, I've included an instructional video as well. This one was very interesting (with nice music) even though the envelopes she's making are a bit smaller than what I tend to use.
I've also seen videos where the crafter used double sided tape to hold things together (and also made larger envelopes), but all of them were very long and not particularly well made, so I hope the website and video above are enough to give you some ideas about how easy this is. I think I'm going to find this really useful this Christmas when I'm looking for package sending ideas (I think I'll reinforce Christmas wrapping paper with either heavy paper or white card stock).
Happy crafting and gift sending!