I know the term "writing utensil", "writing implement", or "writing instrument" can be used to encompass anything you would write with such as pen, pencil, stylus, etc. but I am looking for it's counterpart that encompasses all things you might write on such as paper, papyrus, notebook, clay tablet, etc.
To clarify, I am looking for a word that encompasses the whole thing you write on or in so "writing surface" does not quite fit. For example, the writing surface of a notebook is just the page you write on, not the whole notebook, and the writing surface of a an iPad is just the screen, not the whole iPad.