Building basic kali from script, only the desktop and some essential programs:

https://www.kali.org/docs/development/live-build-a-custom-kali-iso

Decompress the iso and extract the file filesystem.squasfs in the live folder:

sudo unsquashfs -d squash/ -f filesystems.squashfs

from a running copy of the OS itself, mount a few system folders and chroot

sudo mount –bind /sys sys
sudo mount –bind /dev dev
sudo mount –bind /dev/pts dev/pts
sudo mount –bind /proc proc
sudo mount –bind /tmp tmp
sudo chroot .

update, upgrade and manage users. Install or remove programs as needed. Tweak it! Reboot the system and re-zip the folder:

sudo mksquashfs squash filesystems.squashfs -b 1024k -comp xz -Xbcj x86 -e boot

burn a new iso with the newly created filesystem.squasfs