If you’ve ever installed any software on Mac OS X, you’re probably familiar with disk images. They are those wonderful files that end in .dmg which mount a virtual disk drive on your desktop when opened. Disk images are a handy way of storing and distributing Mac OS X files to any number of people, and can be made in only a couple of minutes.
Disk images can be created with the Disk Copy utility, located in HD/Applications/Utilities. Select Image > New Blank Image from Disk Copy’s menu. Then, you can select a name and location for your image. You will also need to specify a size. If your guess is too low, you’ll have to create a bigger image later. If your guess it too high, you will waste a little space.
Optionally, you can specify an Image Layout. For most purposes, no partition map will work. Another option is Encryption. This allows your image to be encrypted based on a password, which is a great solution for sending or storing sensitive information.
Once your options are set, you can create the image. Using it like any other image will mount it on your desktop, allowing you to add and remove files as you please. When you’re all done, unmount the image (select it an press Command+E) and send or store the .dmg file.