Any Size Zipper Pouches by Valori Wells Finished size varies (example is 8in x 8in x 1in)  are my go to container for small and larger items.

The length of the zipper determines how wide the bag can be.

The shape of the bag can range from a vertical rectangle square, and horizontal rectangle so you become the designer.

Fabric choices can vary from decorator weight, to canvas to quilting cottons. If you want to give quilting cottons a bit more body use Shape Flex interfacing. It is a light weight-weight, woven fusible interfacing. Think about what you might want to put in the zipper pouch and have fun!