Our knight collection needed a place to play. Correction, we had a cardboard box, and a some time to kill.
First I cut the box.
Then they painted.
Then they cut out pictures from the knight catalogue.
Finally we stuck and coated them on with modge-podge.
Its more than just a fun craft project. They spend ages studying the pictures, talking about the knights and their horses. It is used as a castle and a horse stable. Also, it doubles as a storage box for said horses and knights. I don't think we could have gotten better mileage out of a castle from the toy shop.