Sorry, maybe I write in circles sometimes - so, to rephrase what I said:
Your original post seemed to say that you wanted to make copies that would work on any Mac. If you have a 'toast' image, you can use that as is on most Macs, or change the extension to an .iso, which again, can be used on most recent Macs, or change to a .dmg, which will give you use on most any Mac running OS X.
So, .dmg is probably optimum, but the other two will work without much difficulty.
Any of those image types can be burned to a CD or DVD, which you can then use on any Mac, no problem.... again - depends on what you have, and what you're doing with that image.
It just depends on what you want to do (which you haven't offered yet.)