First of all I tried some samples from the firmest of the fabrics I used for the stitched samples, to test if the bags could retain their shape if constructed directly from cotton fabric. They collapse gently so I need to find something to help them keep their shape.
I backed the fabric stitched samples with felt and this works. Thinking things through this is going to be the only way to do this if I use textured pieces. I won't be able to sew the felt and fabric at the same time, as one piece of fabric nor will I be able to quilt the fabric - both would affect the outcome of the textures and detract from the effect I am aiming for.
I tried sewing some of the textured pieces to other flatter fabric samples. Making the textured pieces is time consuming (the best and most interesting results come from hand stitching), and as each piece is drawn together at the end to achieve the texture, each piece ends up a lot smaller. So I think their use will have to be restricted to feature panels or even to use as part of an outward facing seam (extreme 3-d effect!!).
I drew some test patterns for the bag side panels:
Finally I started to add some tonal patterns to some of them to begin the process of finding the right final design. I need to spend more time experimenting here, maybe doing some more samples, especially for areas where I wll end up with several small pieces.