i decided to build my own system with i3wm, i think scratch is the way to go. is there any documentation on how this works or something i can follow? from my understanding is that this will allow me to make my own installer ISO or am i mistaken?
Calculate Linux Scratch is best. You can use the cl-builder* utilities. Unfortunately the guide is not translated into English. There is a video where step by step is shown how for example you can replace the browser and recreate the image. Unfortunately the movie is shot in Russian locale, but you can see the meaning of the executed commands https://www.youtube.com/watch?v=zYg_jeME1Nc