I too would like to do the operating system, a lot of the low level coding is already done, we just need to write a bit more of the kernel, then some drivers and then setup a disk filesystem. I made my own custom filesystem because I am trying to make it as difficult for myself, and the development team as possible. However there is tons of work that needs to be done on it, so if you're up for it, then sure.
But it's a fairly advanced topic and would require a lot of studying on each segment before it has been written, and we can't afford any messy coding, at least not in the kernel.