How to develop a product?Practice has shown that many participants in the design teams are not aware of the complete design process. The participants usually have a specialized task. Knowledge of the entire design process is lacking.This book provides insight into the methodical design process as it is applied in companies.Why this book?As lead engineer and project leader I often had to explain to the team members what their role is in the design. Also, the manufacters, who were involved in the design at an early stage, had no idea of their role in the design process. Very little attention is paid to this in education and in the professional literature. Much attention is rightly given to the theory of design itself, but not to how to realize it. I have written this book to share my many years of experience in this field.“If you can’t explain it simply, you don’t know it well enough.” In the book, to explain the process, this rule of thumb is followed.This book provides insight into the entire design with a simple example: the child catapult. The appendix contains a children's coat hanger to make yourself. After all, one learns the design methodology best by doing it.