I'm designing a large (around 40 by 30 by 7 cm) gusset bag from 2 mm vegetable tanned leather. I'm using a three-piece gusset design for added rigidity. I know from experience that large bags like these will eventually start to become rounded at the top as the bag starts to form around your body.I would like to prevent this as much as possible, keeping the box-like form as long as possible. The best solution I have thought of thus far is making the lid a separate piece and hiding a slat of