There are a variety of materials available, and they are welcome to ask for anything they think of that they don't see. But the fabric is very, very, popular.
This is a process that takes a few days, and the children have to be reminded of what they put on the previous page much more so than when they make their own simple books with drawings. Some children have a story in mind at the beginning, but others are just making it up as they go along. Other children have collaborated with the child next to them, deciding that their pictures are part of one story -- "I also have a princess with long long long hair!"
The children are really enjoying exploring the different mediums - and I am feeling more confident about how I am helping them guide the project.