As 4D evolves to support modern software development practices, the need for build automation and reproducible deployment pipelines becomes essential. Introduced as a 4D component by the 4D team, Build4D helps developers automate the process of compiling, building, and packaging 4D applications. It plays a crucial role in integrating DevOps principles into 4D workflows by allowing scripted control over creation of standalone applications, components, and client/server binaries. This technical note provides an overview of Build4D, explains how it works, and presents practical examples of building various types of 4D projects.