Plastic

From LSWiki

Plastic

   Phase: Solid
   Rarity: Very Exotic
   Properties: Organic and Polymer

   No specific help is available for this material.

   Development Information: The black plastic material was created by Lost
Souls; the source code was last updated Tue Mar 15 02:18:42 2016.

Found on old Garbage Thond disposal units' buttons, a few cubes (puzzle fill-the-path cubes IIRC), developers' nerf guns and arrows shot from those, as well as indirectly in the form of nylon, for example in Dracula's Castle's rug.