Did you know that it’s possible to burn to one CD or DVD multiple times? The trick is to use the “Leave Disk Appendable” option in Disk Utility, located in the Utilities folder on every Mac. First step is to create a folder and fill it with the stuff you want to burn. From there, open up Disk Utility (Macintosh HD/Applications/Utilities), pull down the File Menu, select New, and then Disk Image From Folder in the sub-menu.
When the resulting window opens, find that folder you just created and click the Image button. Select a destination for your image, and click Save. The disk image, ending with .dmg, will shortly appear on your desktop and along the left side of the Disk Utility window. Click once on its icon in Disk Utility, then click the Burn button at the top left of the Disk Utility window.
Here’s the trick: When you click the Burn button, a dialog box will pop up asking you to insert a disc—go ahead and insert the disc, then click the blue triangle on the right side of the window and click the box next to Leave Disk Appendable before hitting Burn. Next time you need to burn a disk, just repeat the process; when you get to the final step, the button will say Append instead of Burn.`