I'm trying to draw a mockup of the new ipad in SW, but with the little experience I have I can't figure out how to get the back edge to round off the way it does in the drawings: http://devimages.apple.com/resources/cases/dimensions/iPad-2-WiFi-dimensions.pdf

I've tried doing a swept, and that looks almost right, but it intersects with itself when I get to what appears to be a similar radius on that edge.  Can anyone help me out on what the best way to match that rounded edge would be? 

Thanks in advance.