I used painters paper I got from a hardware store, 9' x 13', if i remember correctly.Its hard to find a single sheet that big. The paper is a bit too thin and weak, i would have preferred something a bit stronger that could have held up to a bit more abuse. I had originally intended to make it stand up against a wall on its own. Im using tape now.
I really like it as an exercise in creating a fluid object. It naturally seems to flow on any surface its put on.