You can do it on a VM, just make the hard drive is big enough. There will be two OS's on this VM for a while.
The original Linux that you are building from, and the custom Linux that you are building.
It's not really "lessons", it's just building additional packages until you get enough of an OS to run on it's own.
Once you get most of the stuff in your rooted environment, then you can copy it over to it's own VM.
My personal opinion, is that what makes a good distro is package management.
If you can figure out how to do all the library and package dependencies for every other package without conflicts, then
the rest is easy. <amaging system OS and package updating as a one man show is very time consuming and difficult.
It can be a full-time job ( with no pay )
