Here's how to create a backup OS X Lion and Snow Leopard installer on a regular USB thumbdrive, so you can leave the extra-tiny one that came with your Macbook Air safe and sound.
The first thing you'll need is an empty USB thumb drive or SD card that has at least 8GB free. Just about any of these will do, but some USB thumb drives with special built-in boot partitions might not work.
You’ll want to select a USB thumb drive with no special boot characteristics. You should also seek one rated with the best hi-speed read/write performance possible.
If you go the SD card route you should also select the fastest possible media (i.e. Class 6 or 10) and look for one that offers a read/write lock switch. I’ll be using a 32GB SDHC Class 10 SD card for this How To.
Insert a blank USB thumb drive or SD card and the original white USB thumb drive that shipped with your MacBook Air Late 2010 model into the available USB ports, USB hub, or SD card slot on your Mac.
Launch Disk Utility from Applications >> Utilities.
Click on the blank USB thumb drive or SD card within the pane on the left side of the Disk Utility window.
Click the Partition tab between Erase and RAID and change the Volume Scheme to 1 Partition. Change the name from the default Untitled 1 to Mac OS X Install and make sure that the Format reads: Mac OS X Extended (Journaled).
Click the Options button and select GUID Partition Table and click OK.
Click Apply, click Partition, and Disk Utility will format the USB thumb drive or SD card.
Launch Terminal from Applications >> Utilities.
Then enter the following commands in the Terminal window and press ENTER after each one:
defaults write com.apple.Finder AppleShowAllFiles TRUE
Open Apple’s thumb drive and look for MacOSX.dmg and double-click it to mount it on your desktop.
Launch Carbon Copy Cloner from Applications.
Clone the mounted Mac OS X Installer Image (source) to the new USB thumb drive or SD card (targets). Accept all of the defaults in CCC, but make sure that Delete items that don’t exist on the source is checked.
Click Clone and you’ll see the following warning.
Verify that you’ve selected the correct target disk and press Continue. A prompt will appear asking you to enter in your password.
Enter your password and allow the cloning process to complete. Depending on the speed of your Mac and the media you selected this is a good time to go grab your favorite beverage and play some Angry Birds.
Unmount the Mac OS X Installer image by dragging its icon to the Trash or by right-clicking its icon and selecting Eject.
Go back to Carbon Copy Cloner, but this time clone Apple’s USB thumb drive (source) to the new USB thumb drive or SD card (targets). Important: before starting make sure that Delete items that don’t exist on the source is not checked.
Switch back to the Terminal window that you had open from a previous step and enter the following commands in the Terminal window and press ENTER after each one:
defaults write com.apple.Finder AppleShowAllFiles FALSE
Once this entire process is completed you’ll have two icons appear on your desktop. If they both look like Apple’s white USB thumb drive icon then you now have a bootable backup of Apple’s Mac OS X Installer on your own media and you can leave the Apple one safe at home.