Ben, those are all separate parts in an assembly and their movements is controlled by angle mates.
I had been thinking of putting up a step by step tutorial but not getting enough time. Hopefully will take that from my to-do list very soon.
I have been asking for this to be something SWX incorporates into sheet metal for several years now during the Top Ten List voting. I don't expect it to actually make it into the top ten, but since that list is a defacto place for enhancement requests along with the clarifying discussions for the ideas I'll continue doing do.
Add an unfold feature for each of the bends. Then suppress/unsuppress each feature as needed in the timeline.