My four year old is very into princess' and castles. She also loves arts and crafts, and frankly, I hardly ever do them with her. I decided she would love to make her own castle. I saved toilet paper rolls and paper towel rolls for a long time, and when I had enough we made a castle. I had not plan in mind, and was pretty skeptical when we started, but I am happy with how it turned out.
my four year old helped me tape all the rolls together with masking tape, in the shape we wanted. I then used spray adhesive to cover the rolls with scrapbook paper (I originally planned to let my daughter paint it, but did not have the right kind of pain on hand, and really did not think it would turn out too cute). The spray adhesive and paper worked great. Then I used a bunch of scrap ribbons from other crafts, and I happened to have a random bag of jewels. I plugged in the hot glue gun and we went to town. I let my daughter choose where everything went, and I would put a dab of glue down and she would glue it on. I also had some hot glue that is colored and glitter, so we decorated the cardboard with it. We had a lot of fun, and we are pretty proud of how it turned out.