Build Gear is a lightweight build tool for building embedded firmware. Its primary focus is to make it easy to create and maintain fully-customized embedded firmware. This is reflected in a straightforward commandline interface and support for easy-to-understand build files. The secondary focus is build performance and build integrity. Build Gear is easy to use and well-suited for rapid prototyping and product development of GNU/Linux firmware to be deployed in small-to-medium-sized embedded systems.