In the first Spider-Man: Far from Home trailer, we get the Peter Parker's friends commenting on Mysterio being "Iron Man and Thor rolled into one." As it turns out, the design for Mysterio's outfit is actually based off of several Avengers in the MCU.
Fandango was able to make a visit to the set, and when it comes to Mysterio's look, they write:
Influences for Mysterio's suit came from Thor, Iron Man, the Vision and Black Panther, according to the costume FX team, with the cape being modeled after the god of thunder's, and chest armor being something Tony Stark might make. Now, that could just be, as they said, "just to keep it all in the same realm, to see that this little superhero lives in the same world as the rest." But within the film, Mysterio seems himself clearly visually inspired by the various Avengers as far as how he designed his own super suit.
A lot of comic fans are already convinced that Mysterio is a hack who was behind the Elementals and is using them to gain fame as a superhero. I guess it's pretty interesting that his costume should emulate the heroes within the universe as well; probably as a way to make the people subconsciously associate him with the likes of Iron Man and Thor.
Of course, Mysterio isn't complete without his fishbowl helmet, and it's the very key element that makes the character who he is. Director Jon Watts says, "We tried a couple different things… but the second you take the fishbowl away, it stops being Mysterio. That's one of the key visual concepts that make him Mysterio."
With Endgame now in theaters, it should be smooth sailing for Sony on the way to the release of Spider-Man: Far from Home. Let's just hope they don't release any further trailers that spoil the film like they did with Homecoming.
Spider-Man: Far from Home hits theaters July 2.
See Also: Spider-Man: Far from Home Producer Insists Mysterio is Peter Parker's Ally