For this process to work, the following are required:
- A purchased copy of Mountain Lion in the /Applications folder
- An 8Gb USB stick
The first screen asks you to select which version of OS X you want to create a bootable USB stick for (10.7 and 10.8 are supported). I selected Mountain Lion (10.8).
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The next screen asks you to confirm which OS X ML copy to use, since it picked the correct one for me, I just continued by selecting Use this copy.
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This screen asks whether you want to create a DVD or a bootable disk, since I have no optical drive, the only option is to create a bootable disk.
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Next I selected that I have an 8Gb USB stick.
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Here it asks to pick which USB stick to use to create the bootable disk. I've already had my stick plugged in, it was named 'USB'.
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Before actually erasing the contents of the USB stick, DiskMaker gives a warning, I selected Erase then create the disk.
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The next bit takes quite some time (15 mins or so). DiskMaker will copy all of the required files to the USB stick now.
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After the copy is completed, there is a final screen where you can make a donation for using the app, quit or open startup preferences.
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Using Lion DiskMaker is a painless way of creating a bootable OS X Lion/Mountain Lion USB installer.
I give it 4/5 stars.
-i