I attended this, yesterday:
I learned so much. I've wanted to go to the previous events of Guardians of the Galaxy 2, Wonder Woman and Spider-Man: Homecoming, but missed those. They're having one for Black Panther and I'm definitely going.
Here, the lead visual developer, Andy Park, who has been with Marvel Studios since Captain America. This is the second project where he's the lead (first being GotG2). You've seen his work for many of these films. What was illuminated was the design process for: Thor, Hela, Stan Lee (they seriously went through a costume process that was hilarious), Valkyrie, Grandmaster and his ship(s) various side characters. Another thing was and I could tell by just watching this movie, this was a love letter to Jack Kirby. A lot of Kirby's work was brought up and displayed during this presentation. Kirby is ALL OVER THIS MOVIE and that made and makes me so happy.
Anyways, this punctuated my belief that Marvel Studios has one of the best visual development teams working today.
Note about Hela's costume: There was a costume made (and I saw it at this last SDCC), and Blanchett is wearing it in a few scenes. But yes, she (and her stunt double, Zoe Bell) had to wear the mocap outfits mostly.