Reed Richards ( Mr. Fantastic) is the creator of unstable molecules. It is a molecular fabric that is able to adapt to a wide range of extreme matter and energy transformations without losing its original integrity.
It is the fabric that composes the costumes of the Fantastic Four and some of their hero allies in the Marvel Universe.
As of FF#1, third generation unstable molecules were introduced. A new feature is that the wearer can vary on the costumes theme just by
concentrating on it.