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This is the way to go: Ned Hutchinson post.
One of the huge advantages of Sheet Metal tools is the automatically generated flat pattern - it saves a lot of time for tool makers.
I am aware of sheetmetal tools, but I have never used it. I was trying to stick with what I was a bit more familiar with, but if needed I will go that route.
You can model this part with diff. approach, but Ned's model is a nice way for sheet metal flat-pattern
Here is another way - see att. model - just overlay your model
Have you thought about sheetmetal tools.