In this tutorial you will learn how to create a bootable OS X Mountain Lion 10.8 Installer USB drive. This way you will be able to install to install OS X Mountain Lion 10.8 on the MacBook Air, for example, without using an external USB SuperDrive. 1. Download a copy of OS X Mountain Lion 10.8 You can download OS X Mountain Lion from the Mac App Store . 2. Extract the contents of the OS X Installer App After the Mac App Store has finished the download you can find the OS X Mountain Lion installer app in your Applications folder. You can now right click (ctrl + click) the OS X Mountain Lion installer app and select Show Package Contents . Open the Contents folder then the SharedSupport folder. This is where you will find the InstallESD.dmg file. Copy this file to your Desktop. Make sure you use Copy and Paste , simply dragging the file to your desktop might only create an alias. Double clicking the file you have j...