Polycarbonate

Polycarbonate was a material. The handles of the M8 Combat Knives used by the Galactic Republic's clone troopers during the Clone Wars were made of flat black polycarbonate.

Behind the scenes
Polycarbonate was first mentioned in the new Star Wars canon in Rise of the Separatists, a 2019 supplement to Fantasy Flight Games' series of Star Wars roleplaying products. It previously appeared within the Star Wars Legends continuity, where it was first mentioned in the 2013 Star Wars: Edge of the Empire supplement Enter the Unknown, which was written by Sterling Hershey.