This book creates a new perspective on the design of plastic parts. In many books there is a strong focus on the material, the material properties, and the calculation or dimensioning. What is often not taken into account is that very many plastic components only have to withstand low loads; in very many applications, the focus is on the actual design. This requires a good understanding of the injection molds that must be built to produce the plastic components. Depending on the design of the injection molded component, these molds become more complex and more prone to failure during production. The complex process of manufacturing a plastic part becomes holistically understandable as a link is created between the molder, the mold maker, and the part designer. The focus is on injection molds and therefore on thermoplastics. Everything that is necessary for the design and manufacture of an injection molded component is presented in a simple, extremely practical manner and limited to the essentials. Many descriptive pictures as well as examples based on the demonstration component "Polyman" facilitate the understanding enormously.