In the book, they mention one of the traps was the "Leprechaun Be Gone 3000TM." I thought this provided the perfect opportunity for my students to engineer their own Leprechaun Be Gone 3000! We used the Engineering Building Blocks again not only because they have been asking since our sloth bed-building, but also because I feel they lent themselves really well to building a robot. They loved the activity and came up with some great designs (including using the wrenches as part of their designs)!