leatherette material

2

…The patches used in the series–slightly narrower in shape than those used in the pilots–were made of a copper-gold leatherette material that had a grapefruit peel-like pattern. After cleaning, they developed a minor degree of wrinkling on the surface. Because of this, most replica patches, like those later sold by Gene Roddenberry’s Star Trek memorabilia company, Lincoln Enterprises, are manufactured with that wrinkle pattern.

Star Trek Costumes: Five Decades of Fashion from the Final Frontier, Paula M. Block and Terry J. Erdmann