How to add a zipper pocket to any bag pattern

So you have a basic purse pattern, or have a pattern that includes a basic slip pocket and you would like a zipper pocket. Not a problem – this sort of thing can usually be added to any bag. You can add them on the outside or on the inside of the bag in the lining. Or both if you want lots of pockets and storage. The exposed zipper can really add a nice pop of color and an interesting design feature to any bag.