My recommendation for the cardboard is purely because it's easy to cut to size for the scanner bed and you can keep it under the lid when not using it. I had originally included the phrase "and put a book on top of it", but I managed to edit that one back out again somehow. A magazine sounds like a good compromise (I don't have such things around my house, so I wouldn't think of that). Scanning is hard business, but the results can be well worth it!