From the wide range of sources offered by the open source community, emlix first makes a reasonable selection for a particular project. On the basis of long-standing experience, emlix also defines a well suitable "recipe" that specifies within e2 factory which patches, configuration switches and interdependencies will be compiled into further packages.

In order to make the build process reproducible and independent of the computer used for it, e2 factory provides an individual build environment. In technical terms, this is a chroot cage containing all the necessary tools, such as compilers and make tools. In the build process, the sources are treated in the build environment according to their respective recipe. In this process, subpackages are created, which in turn can be used as an input for further build processes (e.g. header files or libraries).

In order to exclude any interactions between the build processes of different packages, a new chroot cage is used for each process. Therefore, each version always consists of sources, recipe and the corresponding build environment.