This children's book is about Ellie, a natural engineer. Ellie loves to complete a variety of “builds,” including time-saving devices, like a French braid machine that does not work quite as planned, and a trap to stop snooping brothers. The story begins with Ellie and her best friend, Kit, completing a build of a water-balloon launcher to teach the neighborhood boys that it is not okay to exclude the girls from the soccer game. When Ellie's birthday gift for Kit, the French braid machine, acts more like a hair tangler than a hair braider, Ellie realizes that she needs to make a new gift for Kit, and fast. Ellie then comes up with the best idea ever: a fancy doghouse for her fancy friend's new dog. However, unable to ask Kit for help, she turns to one of the neighborhood “jerk boys,” who turns out to be not such a jerk after all. Unfortunately, Ellie feels that she needs to lie to Kit to keep her secret, and she then lies to several of her friends, creating an unpleasant situation with many hurt feelings that Ellie must navigate. Fortunately, the kids successfully build the doghouse in time for the party—it even has a waterslide—and everyone, even the boys, get to go to Kit's party to experience the final surprise of the book.

This is a fantastic story for children about 6–12 years of age and is especially suited for girls. Ellie is a strong role model who emphasizes that you do not need schooling to become an engineer (well, maybe for the really tough builds) but instead just a desire to create and a willingness to make and fix your mistakes. The book also deals with themes of exclusion, like when the boys won't let the girls play soccer, or when the girls neglect to invite the boys to Kit's birthday party, and why lying is not a good option. There are drawings throughout of Ellie's builds, and there is a guide to Ellie's favorite tools at the end, starting with safety glasses. It also has humor and a few action scenes, keeping the story moving. I will be encouraging my own son and daughter to read this book, and it would be well received in many elementary classrooms.