Free sewing pattern for an easy cross the body bag from Sew Different. Make lined or single skin. Have a look at the blog post for pictures and "how to"
origami folds help create this package
Easy DIY Oragami Bag. Need one large piece of fabric (17" x 51") and a small piece for the handle. Shape is made by folding, only a few seams required.
packaging origami - Cerca con Google
Double Case More
Inspired by the Japanese art of origami, the now Berlin based designer (born in Mexico, raised in Argentina, college in Japan… phew!), Ayako Hase, has created a bag that can be folded and transformed into different looks and uses.
origami bag tutorial. i would use a heavier fabric and add a liner, but otherwise this looks great! and easy.
origami oasis bento bag cutting & sewing instructions
Tasche aus quadratischer Grundform (Schnitt: http://www.textilhemmers.de/blog/geometric_bag_-_naeh_mit_uns.html)