While it’s hard to make the claim that there aren’t enough Linux distros out there, it’s also hard to escape the fact that no distribution is all things to all people. There are all kinds of reasons to consider rolling your own, but many people never make the attempt because it seems like such a huge undertaking. Fortunately, with modern software we can create new distros, remixes, and custom configurations in a matter of minutes instead of months.
6 Tools to Easily Create Your Own Custom Linux Distro – Make Tech Easier.
Good set of tools that let you essentially clone your Linux setup. Appears to be aimed at desktop setups, but may be useful starting place for building custom distros for servers.