Remember how I said I’d write a tutorial? Well, here it is!!
I used a 12-14” invisible zipper. You could also use a regular ol’ zipper too. Figure out where you want the zipper. You probably want it somewhere toward the top but do not go so high that you get right next to the seam allowances.
Cut out a second piece of fabric that will go behind your zippered piece. You can see here I basted my zipper opening closed. Otherwise, there is a the very real possibility that you will forget there is no zipper stop and pull your zipper head right off. Don’t do that, it’s annoying.
Baste the two layers together and treat them as one piece for the remainder of the construction process. My serger dislikes going over plastic zipper tape, so I always also go over this seam with my sewing machine to make sure those stitches won’t come out. Also, if you are using a metal zipper you SHOULD NOT sew over it. You need to remove the zipper teeth.