I used left over stripes for the cloth body and cut a piece of heavy plastic out of one of those zipper bags that you get your sheets or bedding in.
While I only left about a three inch hole to pour the rice through, I ended up sewing all across the end to make it look a bit nicer. I figured machine stitching is going to be more secure than me invisibly hand stitching it closed. It's not a total fail though. We had some impromptu babysitting to do today and the new toy went over very well.