M,
That's a very nice tutorial . I'll have to give it a try( very soon).
Just reading it . I can think of an additional stage that may aid assembly. From experience I'm fairly certain it would. But I'm old enough and daft enough to know that until I try. It should remain 'fairly'.
I'll mention incase it's longer than I anticipate to find the time to build an 'onion' dome following your tutorial.
Once you've folded along each dotted line. Precurve each Petal before moving onto assembly. It should make it easier to join each Petal of the dome once the dotted line cone has been assembled.