I started out by making a pattern out of felt and stitching it up to make sure it was just the right size. Then I reproduced it out of heavy duck cloth. Each piece has a two layers of duck cloth with a heavy weight stabilizer in the middle.
All the edges are trimmed with a strip of bias cut duck cloth folded in half. I left the raw edges exposed to make it easier to sew on the binding. They will fray a little as it wears. On the back I sewed a strip for a belt to slide through.
Anyway, it was a fun adventure. There is just something so satisfying in sewing up something useful!