[Suicide Junkie]

For example, when I wrote CBmod, I did it mostly from scratch... IE, I started with a set of blank files and a couple pages of hand written notes and typed stuff in.
The mostly part is because I started with settings, intel, systemtypes and sectortypes, and merely edited them heavily.

The most difficult part of doing a mod from scratch is that you have quite a bit of work before you can do much more than load the main screen and check for typos.
The benefits of having a blank slate are quite significant if you've planned out your universe physics and balance beforehand.