EBuild is a new cross-platform build tool chain that we are working on for a future version of Elements. When it is ready, EBuild (and with it large portions of the Elements-specific tasks and tool chain) will be open-source and available on GitHub.
Ebuild will replace our use of MSBuild and xbuild within Fire, Water and Visual Studio, and allow us to be much more flexible and innovative with our build process. Probably for Elements 10 "Intrepid".
Fire 9.1 already uses a technology preview of EBuild, not for the build process itself (although you can enable this experimentally to try it out, as well), but for resolving references inside the IDE. This is most notable with the advanced display and handling of Gradle and NuGet package references.
Stay tuned to this place for more information, soon.