First mentioned in 2014 and making a proper introduction in the first issue of the Superior Iron Man comics a year later, Tony Stark developed a suit based in part on symbiotic biology (yes, by “symbiotic,” that refers to the same Symbiote that gave Peter Parker his black Spider-Man suit and turned rival photographer Eddie Brock into Venom) which allows it to contour perfectly to the figure of any wearer.
Being made of liquid metal, this armor would have also made for a great reference to Robert Patrick’s antagonist in Terminator 2: Judgment Day somewhere in the MCU movies.