Plastasteel

Plastasteel is a self-molding material used by the UNSC to make objects shape into handgun grips.

The material is also used to make the shells of cryotubes.

Trivia

 * Although it is not directly called plastasteel, the material that makes up some chairs in Halo: The Fall of Reach is described very similarly, and shifts to fit the shape of the user's body.