The world is full of interesting projects, and you have to do triage or go crazy with too many things to work on. While I have a fair amount of experience with build systems (starting with a public domain version of make that I wrote in the early 1980s for Vax/VMS and MSDOS), it's not something that I want to spend a couple years on.
On the other hand, I complain enough about CMake, Gradle and similar tools that maybe I should. I've got some ideas to try out . . . . :-)
It'd be nice to see those ideas realized. I have some ideas myself but haven't started anything yet because I've been focusing on my studies. I already have one small project that I work on in my free time.
My problem with most build systems is they're general purpose tools. I need to teach them how my projects work every single time. It'd be so much nicer if I could encode my conventions on the system itself.
Starting a new project should be as easy as initializing a git repository and putting the right files in the right directories. The build system should be able to at least figure out where the sources are based on convention and determine the dependencies between files.
On the other hand, I complain enough about CMake, Gradle and similar tools that maybe I should. I've got some ideas to try out . . . . :-)