Final answer:
The custom build script for building the kernel generates files like the kernel image (vmlinuz, bzImage, zImage), kernel modules, System.map, and the build configuration file (.config).
Step-by-step explanation:
When a custom build script is used for building the kernel, it typically creates several files which are necessary to run the new kernel. The most important of these is the kernel image itself, often named vmlinuz, bzImage, or just zImage depending on the architecture and the build configuration. Additionally, modules that have been compiled to add functionality to the kernel are created. These are usually located in a directory structure under /lib/modules//. Build scripts could also generate various other files such as System.map, which maps the symbols and their addresses in the kernel, and .config, which is a copy of the configuration settings used for the build.