Robert Downey Jr. doesn't mind talking about the Marvel Cinematic Universe. The actor was recently interviewed and broke down some of the secrets behind making Avengers: Endgame and some of the other projects in the MCU. Downey Jr. started playing Tony Stark on the big screen back in 2008 when the first Iron Man movie hit theaters. He's now done with the role, but he has no problem going over his experience working with Marvel Studios and the "curated" group of actors he was fortunate enough to work with over the years.
A lot of the MCU is made up with the use of computers. Tony Stark's Iron Man suit is mostly CGI, which Robert Downey Jr. freely admits. When asked about working in the digital realm, RDJ started by talking about his work on Richard Linklater's A Scanner Darkly, which was done using rotoscope, which is an animation technique that animators use to trace over motion picture footage, frame by frame, to produce realistic action. The rotoscoping "is a great metaphor for essentially what the Marvel movies became," says the actor. And he also equates that role with igniting his MCU career as Iron Man.
Robert Downey Jr. went on to talk about how easy it was for the digital team behind the MCU to manipulate things, even going as far as being able to move his arm during a shot. This led to talks of the original Iron Man set suit, which was basically like a football uniform with all of the padding. When asked why he couldn't just wear the motion capture dots, he was told that the suit was for reference. So, he would do one take in the suit, and then do another without it, so he could move around more freely.
Mark Ruffalo had it pretty easy while playing Hulk and Smart Hulk in Avengers: Endgame, though he at times wished he had something to wear around his waist. Robert Downey Jr. notes that Ruffalo wore a motion capture suit, which had a PVC pipe coming up the back with a Hulk mask a couple of feet higher than the actor's head. This was to give the Russo Brothers an idea of just how big Smart Hulk was going to be on the screen when the digital rendering was complete.
While working in the digital realm can be tricky at times, Marvel Studios has a pretty great creative team working with them. Plus, as Robert Downey Jr. says, the whole list of collaborators is carefully "curated," making for a nearly unstoppable team. Without the performances from the actors, the CGI effects would all fall flat. Josh Brolin was Thanos, even though he was walking around in a motion capture suit the whole time, and the same can be said for Mark Ruffalo and Hulk. You can check out the interview with Robert Downey Jr. below, thanks to the Joe Rogan Experience YouTube channel.