To do this, I cut up an old laptop case for the body, and an old belt for the sides. The belt leather is quite a bit thicker and will help the bag to stand on it's own. I then ironed folds in the leather to define the edges of the bag.
Using super glue, I glued the first piece of the belt leather to the bottom of the bag.
I then glued the sides in place...
and glued the sides to the front...
and finally back of the bag. Very simple.
I wanted to add straps to give it a little more character so I cut some thin strips of leather out of the old laptop case.
I took a paper clip and bent it around the rounded edge of a pair of needle nose pliers to make...
tiny metal loops for the straps.
I then glued the rings into the small straps...
and glued them to the front of the bag. I glued the long straps to the backside of the bag and threaded them through the metal loops on the front. Finally, I added a metal button to the front flap.
Using sand paper, I roughed up the leather to make it look well used. And that's it!