lxnay@gentoo.org Fabio Erculiani Metro is a build tool that can build, rebuild or extend Sabayon Linux or Gentoo Linux OS releases OpenVZ templates and stage4 tarballs. It doesn't contain any specific package manager bit and can work with your favourite one. The philosophy of Molecule is simple: ease of use and modularity. Just like Catalyst, Molecule uses its own .spec file format and learning how to write one is just about reading examples provided inside /usr/share/molecule/examples. You can tweak your ISO image or create one off your chroot (stage4) in no time. Molecule uses a plugin-based system to implement support for new execution patterns (like ISO to ISO, ISO to Tar, Chroot to ISO, etc). Molecule is born inside Sabayon and is used in its release cycle for both daily(live) and versioned ISO images. Molecule developers are looking for help for writing user docs and HOWTOs.