My sons, ages 7, 13, and 15 all love Lego. We have a huge bin of Lego that they build from. 1000's of pieces. For this book, technic bricks are required for most of the projects. Though the projects are not made of all technic bricks. We purchased the specific technic pieces for the projects, a lot of them are used in multiple projects. You can go to a Lego store to purchase specific parts or you can get them through online sources. We spent $50 on buying a fair selection of the technic bricks for the book, but if you have technic pieces you may not need to by them.I like this series of books put out by Sarah Dees. This particular one has some great ideas to build. My 7 year old son built the Wind-Up Catapult this morning with a little help from his 15 year old brother. They both problem solve when using the book. Usually we can never find the exact brick, color, or parts for the entire project so they problem solve by modifying the idea with what they can find. My 15 year old used his knowledge and created the Wind-Up part with technics but differently then how the book showed and the 7 year old made the rest with whatever color of pieces he could find. I feel these books encourage problem solving and improvisation.I would highly recommend this book for those who are ok with improvising and problem solving to make something work when you don't have the exact pieces the book calls for. It is a great tool to give them ideas of what to build, how to build it and then watch them figure out how to make it from what they do have.I would NOT recommend this book for those who must follow all the directions to perfection and are not able to make modifications as needed. It gives great ideas and good directions, but it can be hard to have all the exact parts needed.One of the cons in this series of books is that the pictures of the builds are small. The author has told me that this is because the publisher wants to get as much in the book as possible, but this can create problems when you are trying to figure out exactly where some of the pieces go. On the other hand, it can bring up opportunities to learn thinking and problem solving skills.Bottom line, if you have kids who like to problem solve, are OK with not making something exactly as shown, and have a good selection of technic pieces then this book would be great for them. It will give them some good ideas of things to make.However, if you don't like to problem solve, want everything to be exactly as the directions say, and don't have technic bricks or the means to buy technic bricks then this book probably isn't for you.P.S. This book keeps my 7 year old occupied for hours because he has to sort through tons of legos to find the right pieces.