You can make a continuous roll of bandaging material from a t-shirt simply by cutting it in a spiral pattern. Begin at the bottom edge and then keep cutting until you have enough. Adjust the width of the bandage so that it fits what you need it to do.
It doesn’t need to be sterile since a bandage is meant to hold things in place. It’s a dressing that is placed in contact with a wound and should, ideally, be sterile.