Thanks for posting the correct link to the boxy bag tutorial, Sewbeeit42! One of these days I will learn how to do links!
and Latrinka, the 12" zipper worked perfect for me--the zipper tape on a 12" zipper measures 13 1/2" which matched up perfectly to the cut dimensions of the fabric and this way you don't have to sew over the teeth of the zipper and possibly break a machine needle. But if you have longer zippers on hand I have seen other tutorials that sew the side seams right over the teeth of the zipper and cut off the excess length. So either one would probably work.
Last edited by Jeanne S; 03-26-2015 at 08:42 PM.