I figured I'd (finally) share this super simple tutorial for a brown paper bag mailer. You could also decorate it and use it as a gift envelope! This tutorial is for standard paper bags you get at the grocery store, but if you're like me and plan on making a bunch of mailers, you can get a roll of kraft paper (I get 50# strength) at a craft store or on eBay. Simple cut a piece 15" by 48", fold in half so it's 15" by 24", then leaving the 3" or so overlap, fold in half again, making an envelope.
You'll need: -2 brown paper bags -an old needle (a new one will work too, but it will dull it) -paper clips or binder clips -sewing machine, thread, scissors, etc
It's smart to keep some old, dull needles around specifically for paper sewing. I store mine in the little thingamajig they come in (be sure to label them so you don't confuse them for a pack of new needles!) But you can keep them in an envelope. Or you can get real clever like Jenn and use a jar to keep your dull needles and pins in!
The next two steps are only necessary if you want a US First Class Parcel applicable envelope. To ship First Class here in the States the package must be under 13 oz. and be no larger than 12" by 15".
Using paper clips or binder clips (as seen here) clip the sides to hold everything in place when stitching. (Molly sent me these cute little bitty ones--they come in handy, thanks!)