Messenger Bag with Interchangeable Skins

In my last tutorial, I taught you how to turn a t-shirt into an Evozip interchangeable skin.  In this tutorial, I will teach you how to make the bag for the interchangeable skins.  Once your bag is ready, you can attach any Evozip skin to your bag.  You can change the design as often as you like or you can create your own skins from old shirts, your favorite fabric or with paints.

Here is how to make the Evozip skin.
http://www.instructables.com/id/Interchangeable-skins-for-messenger-bags/

Step 1 Materials Needed

Here is what you need to get started:
1 Rock,
1 Messenger bag with a front flap that is 15" by 10"
1 Evozip skin,
1 Silver Sharpie,
4 Grommets with grommet tool Size #0, 1/4" inside diameter.
4 Jean buttons or normal buttons if you like to sew.