I'm steeling this from my personal blog cause it gets so many hits from yahoo answers.
I found this explanation:
This is a regular straight sleeve pattern that I already had.
Following fig. 2 above I cut it into 1 inch strips (numbering them so I didn't mess up the order)
Space them out, draw the new lines and you have the outlike for your new pattern.
This is now a puff sleeve pattern, and I didn't have to buy it!
This is not a very good picture, but it's the only one I have. This is the finished sleeve on the dress.