Looking For Flawless Tutorial On Installing Custom Kali Image

Hello...

I brand new to this community but not really that new to Kali Linux (or Parrot OS). However, due to the sizeable amount of information that goes into learning Linux, I'm still in need of assistance now and again. One of the new things I want to learn is how to install a custom Kali image. I was surfing around the web looking for a tutorial or something that spoke in the language of mere mortals but haven't had that much luck?either the terms are a bit confusing or their English is off ... either one. Anyway ... I don't really expect anyone to write me a tutorial in this forum (unless they simply want to for the heck of it); I assume that some Kali Linux veterans would likely know of some decent tutorials on installing custom Kali images or might even have written one themselves that they can refer me to. Thanks in advance.

And one last thing: I was wondering how to appropriately download most pentesting tools. I tried to do so when I was installing Kali fresh the other day, but I kept getting an error right after the install finished eating up all of my data downloading all those tools. I gave up after like the third time because it was just getting ridiculous (data-wise). The only reason why I ask is that I have tried following some short little tutorials but for some reason or another, I kept coming up short on one thing or another.

Again ... thanks!