I've noticed that my posts that offer tutorials and advice get lots of traffic. I'm glad that I might be able to help someone. So today I decided to write about the use of interface when creating handbags. My Wayfarer Purse posted above is made with 3 layers of interface. Interface gives fabric more structure and durability.
For the purse above I used Pellon Decor-Bond, a fusible interface, for the exterior fabric and the interior lining. I could omit interfacing the lining but I like the crispness it gives the fabric and it makes it more durable as well. Decor-bond is a firm iron-on non-woven backing. Some care is needed when ironing it onto the fabric. I would recommend testing it on a small piece of fabric first. If too much heat is applied it can make the fabric pucker. Instructions on how to use it is included with the bolt. I also found this site with some useful instructions. If you are planning to wash the item you are making in the future then you should pre-wash your fabric before applying the fusible interface.
Recently I've starting adding a 3rd layer of interface, a thick fleece-like sew-in, to my Wayfarer Purses, Market Totes and Messengers. This gives the handbags even more structure.
Sometimes less is more. For instance, if you want nice flowing pleats then stiffing the fabric with interface is not recommended. For my Pleated Everyday Bag I only interface the top band of the bag. I tried interfacing the entire fabric once and it gave the pleats a stiff unnatural look. You live and learn! I recommend experimenting and finding what works for you. I hope that I was able to provide some helpful tips!