That's so cute and a great use of the 'scraps'. I always say that quilters don't have trash, we just have pieces that haven't found a home yet! When I make totes for my girls, I don't put heavy interfacing in them. They like to roll them up, throw them in other purses, and need to be very washable. But I do make a removable bottom piece - something very stiff covered on fabric. This allows it to keep a shape, but can be removed for washing or for rolling.