Is the for a school project or do want something functional? I suspect that you are interested in creating your own Operating Environment that is based on any of the current Open Source Operations systems out there to start with.
To create your own operating system would mean that you would have to start with a limited target hardware set and code base and a lot of time.
There are many OS projects out there that would benefit from your energy! Just search from alternative Operating systems and keep looking.
There are FAQ's out there that will help you package your own Linux-based OS. Some are RHEL (Red Hat Enterprise Linux) based, and others may be Fedora-based. Remember that Fedora is where RedHat tests out new stuff, so it is not always totally stable. I think the current Fedora version is 19. It does have newer kernels than RHEL and RHEL-based systems. I run Scientific Linux 6.5 and CentOS 6.5 which are clones of RHEL 6.5. Here is a link to the repackaging tools for Scientific Linux (SL) - they call it building a site version, or some such: http://www.scientificlinux.org/distributions/6x/build/sites/view
In any case, you have a lot to learn and experimentation to do. This project will keep you busy for quite a long time I suspect.