Plasteel/Legends

Plasteel, sometimes called plastisteel, was a material that combined acrylic polymers and metal alloys. Plasteel retained the elastic strength of plastics while benefiting from the strength and heat resistance of metal. However, it was not a miracle substance. Pressed thin enough for comfortable armor, plasteel would not impede a blaster bolt, or even an old fashioned slug. Plasteel was most commonly used in armor, spaceship components, containers, and construction. It was capable of yellowing with age.

The Scarab Droid's body casing was made of plasteel.

Behind the scenes
The word plasteel is a portmanteau of plastic and steel. The term appears in Frank Herbert's Dune series and may have been coined by Harlan Ellison, who used it as early as 1956.