You can easily download Apple’s OS X Mountain Lion from the App Store any time after purchasing it, but its nice to have your own physical copy of the installation so you don’t always have to re-download it when troubleshooting.
Use Disk Utility For DIY Mountain Lion Install Copy
The steps for burning Mountain Lion to a disk are essentially the same as the ones for Lion:
- Download Mountain Lion from the Mac App Store—but don’t install it yet, because of the disappearing installer issue noted above.
- Find the installer in your Applications folder and right-click on it then select “Show Package Contents.” Head to Contents > SharedSupport and look for the file called “InstallESD.dmg”
- Open up Disk Utility from your Applications > Utilities folder and drag the DMG file into the sidebar on the left.
- If you’re burning to DVD: insert your disk, select the DMG file in the sidebar, and hit “Burn.” Skip to step 6.
- If you’re burning to USB, you’ll need to first format the drive properly:
- Insert the disk and select it in the sidebar in Disk Utility. Select the Partition tab, select “1 Partition” from the dropdown menu and choose “Mac OS Extended (Journaled)” for the format type.
- Click the Options button and choose “GUID Partition Table”—this will make the drive bootable and formatted correctly for the Mac. Hit Apply to format—which will completely erase—the drive.
- Now click the Restore tab and choose the DMG file as your source and the USB drive as the destination. Hit the Apply button to make it happen.
- Finally, to boot from your install disk/drive and install Mountain Lion, restart your Mac and hold the Option key down when you hear the startup chime.
Let me know if you have any trouble or if there is an easier way to create a physical copy of Mountain Lion.