We used a paper plate as a mold for the bailey, and just wadded up news papers for the motte. It took over a week for it to dry, probably due in part to our overly enthusiastic helpers, who were awfully heavy with the goop.
Ta Da! The finished result! Anna did most of the work herself, with only minimal help from me, and she is understandably very proud of it. However... I have no idea where to put it. This is when a school room would be really nice.