I made the ship above as a prop for a TV commercial a couple years ago. I assembled some boxes and parts of boxes into a shipish shape and then added all sorts of stuff – pipe cleaners, dixie cups, part of a birthday crown, wooden ice cream spoons, buttons, felt, etc. etc. The castle collage below was for an ad as well. I think they would be fun for little people to make ( with some grown up help).
Both involve using the die cut sections of boxes for details . I can’t resist a good piece of cardboard – I live near a fancy grocery and their recycling is full cartons and boxes with interesting cutouts and shapes.