This book has taken front and center stage since it got here. My boys (especially my oldest one) have great fun collecting things to make their own catapults. We haven't actually started building any because we are in the middle of reading the book, but the instructions are very clear and easy to read. The day it got here, my oldest son was inspired to start writing up his own plans for a catapult. We have been studying medieval times, so this book was a great addition to our family!