Just download the Lion Diskmaker app, unzip it, and run it. (Why not rename the app to something more generic like "OS X Diskmaker"? Gète says he just likes the existing name better, and besides, it's less likely to catch the ire of Apple's lawyers.)
CREATE USB BOOT DISK FOR MAC OS X LION INSTALL
His app automates the process of making a bootable install disk for both Lion and Mountain Lion-just run the app and let it do its thing.
If you find digging in to bundles and using Disk Utility to be tedious or bothersome, you can thank developer Guillaume Gète for making Lion Diskmaker. You can also burn the installer to a DVD-R, but booting and running the installer from an optical disc is s-l-o-w. Other external drives will also work, but make sure the type works with all your Macs-USB is the most universal. We recommend a USB flash drive for your backup installer they're cheap and easy to store and transport. Mountain Lion installer app downloaded from the Mac App Store.An 8GB or larger USB flash drive, other external disk, or 4.7GB DVD-R.Therefore, you need to either make a copy of the installer outside of the Applications folder or make your install disk before upgrading. Important warning: the OS X installer will delete the necessary file needed to make your own install disk once it runs.
We have instructions for those of us who just want to get it done-using the donation-ware Lion Diskmaker app-as well as those that don't mind a little extra clicking to do it yourself. Do you really need to wait 45 minutes or more for each one? Absolutely not! Just make your own bootable install disk using our handy tutorial. Happy Mountain Lion Day! Now that you have downloaded the 4.34GB installer, you may want to install Mountain Lion on more than one of your personal machines.