Hi wendy-lebaron, thanks for the welcome.
Back in the Tiny Core 4.x days, I tried my hand at remastering the Tiny Core initrd, just making some cosmetic tweaks to prove to myself that I could. It was easy and I was all set to really personalize it and have my own personal "vanity" distro.
Then I stopped and thought to myself, "Why would I ever do this?" The developers of Tiny Core, RobertS and his amazing team, have already factored out pretty much everything I would want to modify. Oh, I might throw out "on demand" loading of extensions, since that's something I can't imagine ever using, but that would gain me... -nothing-. A couple of times, I've thought of features that would be really handy to add - only to find out they were already in there.
So, for me, at least, "building my own distro" is a non-starter. I just add to Tiny Core whatever software I need for a given use case and do whatever tweaks I want at boot time.