If you already have the Mac OS X Mountain Lion install DMG extracted, skip this first set of steps and jump directly to making the bootable drive below.
We’ll walk through the process here, but don’t forget to check OS X 10.8 system requirements for the destination Mac before beginning. By creating a bootable install drive, you can perform clean OS X 10.8 installs, install it on separate partitions, and install OS X Mountain Lion on Macs that don’t have internet connections.
