My guild table sold a lot of the snap bags too, all sizes. The bigger ones we made for cosmetic bags. Really over sized. DH gave me an old 1" wide 25" long tape measure that wouldn't go back in the case on it's own. It makes a great snap! for the big bags. We noticed that BIG sells better.
Here is video of one snap bag pattern. They are many free patterns online.
http://www.youtube.com/watch?v=jkdpy5gyf6w