Create a custom debian Live ISO

[Trevis Schiffer <nikolaibitinit@gmail.com>]

Hi,

I am trying to build a custom ISO from this guide: 
https://willhaley.com/blog/custom-debian-live-environment/

But the ISO fails to boot, with a message that it can't find the init 
system.

Then trying to understand: https://wiki.debian.org/DebianCustomCD but 
the whole page is bit overkill for what I want to do.

Do you know any simple, minimalist, up-to-date guide to create a custom 
minimal live ISO?

I want some network audit tools, emacs-nox, zfs-fuse  etc with a sid ISO.