I am looking for manually generating an ELF Core Dump file.
Just use Google elf userspace coredumper, it does exactly that.
I want to build my core dump, not implement it directly into my software
There is no existing program (that I know of) that can do that. Chances are, you'll have to write one from scratch, or adapt some other program.
There are two programs that can write a core dump from userspace -- the above userspace coredumper, and GDB (via gcore
command). I expect that adapting Google coredumper would be much easier than adapting GDB.
Should you decide to write one from scratch, you can still read the Google coredumper source to figure out what it is you must write to the core.