I want to close this book by repeating a quote from Jesse Warden's blog post "10 Tips for Working with Cairngorm" (http://jessewarden.com/2007/08/10-tips-for-working-with-cairngorm.html):
I felt "comfortable with Cairngorm" on my fourth project with it. To this day, I still mod it though, and try different things. As more people come into Flex, there are more cool ideas and techniques floating around.
While this book has come to an end, the process of honing your skills with Cairngorm is just beginning.
While I hope you have found this book an informative and valuable resource that you will turn to in the future, in learning any new topic there is no substitute for practice and experimentation.
Given the variations in things like package structures in sample applications, and the often contradictory suggestions on best practices, it is not unreasonable if some things about the Cairngorm framework are still unclear to you (there are things that still seem unclear to me, even after writing this book).
I would honestly encourage you, if you have not done so already, to download the FStop application (http://download.macromedia.com/pub/developer/f3ic_studentFiles_16Jun08.zip); the Cairngorm store application (http://www.cairngormdocs.org/exampleApps/CairngormStoreWeb2_1.zip); and any of the examples at cairngormdocs.org (http://cairngormdocs.org/blog/?cat=6), and to spend some time simply going through them to see how things are done in those examples. ...