Well, there are a bunch of tecniques out there and tons of styles to make. I guess your question is a bit too broad to answer. SugarShack has a new video out called Boxes and Bows. I've heard nothing but good things about all of her videos!
http://www.sugaredproductions.com/
HTH
Did a search on you tube and found thought this might help answer your questions about how to make a cake box.
There are several videos you can watch enjoy!
http://www.youtube.com/view_play_list?p=07BFE2901FF34466&search_query=box+cake+tutorial
I just sat and watched a couple of the videos for this tutorial and I have to say it is not that good...they seem to make the cake harder than it actually is.
Take the video's with a grain of salt !
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