

Follow Steps 1 through 4 in this slideshow to properly format the drive. This drive must be at least 5GB in size (an 8GB flash drive works well), and it must be formatted with a GUID Partition Table.

Connect to your Mac the hard drive or flash drive you want to use for your bootable Lion installer.Drag the Mac OS X Install ESD icon into the Source field on the right (if it isn’t already there).Click Mac OS X Install ESD in Disk Utility’s sidebar, then click the Restore button in the main part of the window.The mounted volume is called Mac OS X Install ESD. This mounts the disk image’s volume in the Finder. In Disk Utility, select InstallESD.dmg in the sidebar, and then click the Open button in the toolbar.To create a bootable hard drive or flash drive
