Recently, I've been wanting to make a custom live iso with a couple of tools that I need but I really don't know where to start or what to do… any help?
E: I didn't phrase my post correctly, I need a portable set of desktop tools for development, running on the gnome desktop
Use the live version (thd try without installing option). You can also remove the installer code if you really want to - I think Ubuntu uses ubiquity/subiquity.