Select the plugged USB from the Left pane on the Disk Utility and then go to Restore tab.Double-click on InstallESD.dmg (that you copied onto your Mac desktop) to mount the Lion disk image (mounted InstallESD.dmg should appear on Disk Utility application and desktop).Now click on Apply at the bottom right to start formatting. Select GUID Partition Table and click OK. Now click on Options button at the bottom.

Input a name for the USB and Choose Mac OS Extended (Journaled).Select 1 Partition from the Volume Scheme dropdown menu.Select the plugged USB from the Left pane on the Disk Utility and click on Partition tab.Plug the USB flash drive into your Mac.Before formatting, If you have any data on your USB drive then save it.Locate the file named: InstallESD.dmg and copy it on your desktop. Now go to Contents > SharedSupport directory. Right click on the Install Mac OS X Lion.app file and select Show Package Contents Once the Lion downloading is complete, go to the Applications folder and find the Install Mac OS X Lion.app file you just downloaded If you have arranged the above mentioned items, simply follow the detailed guide below to create a bootable Mac OS X Lion 10.7 USB Flash Drive… How to Make Mac OS X Lion Bootable USB Flash Drive Step 1 – Locate the Lion InstallESD.dmg file Purchase and Download Mac OS X Lion from the App Store.You will have external media to recover and reinstall Lion in the event of total drive failure or some other catastrophe.The bootable Lion USB drive becomes a recovery disk with Disk Utility access, access to Time Machine backups, re-installation, and all other Recovery HD partition features.You can perform a clean OS X Lion installation with the bootable USB drive.Creating a bootable Mac OS X Lion 10.7 USB Flash drives requires medium level Mac knowledge, however, by following these simple instructions even a beginner should be able to install Mac OS X Lion via USB Flash Drive.

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