You already learned how you can pause and resume your OS X Lion download from the Mac App Store. But as soon as your download is over, you will see the OS X Lion install screen that you see in Figure 1, below. Resist installing this upgrade for now, and choose the Install Mac OS X Lion | Quit Install Mac OS X Lion menu option for now.
Why did I ask you to quit the install? That is because it is best that you first create a backup of the 3.74 GB download! Yes, it is true — as soon as you finish installing OS X Lion, the downloaded install file will be cleaned up! You might want to install OS X Lion on other computers, or just retain a backup of the install file — after all, 3.74 GB is not a minuscule size, even by today’s standards.
So head to launch Finder, and go to your Applications folder — it is here that you will find the Install Mac OS X Lion app, as you can see in Figure 2. Note that all applications in this folder, as shown in Figure 2 have the app file extension — this is because I have globally enabled file extensions on my Mac.
Figure 2: The Install Mac OS X Lion app
Right-click or Ctrl-click this app, and choose the Show Package Contents option in the resultant context menu. Within the Contents | Shared Support folder, you will find the InstallESD.dmg file (see Figure 3)
Figure 3: The InstallESD.dmg file
Select and Alt-drag this file to any location on your computer — remember Alt-drag will make a copy, just dragging will remove the DMG from the package — you don’t want to do that! Once extracted, you can burn this image to a DVD. You can also make a backup of this image on an external hard disk.