Once you get further into the game you will start to require Ballistic Fiber for crafting and repairing your higher-end armor. It can usually be found in military sites in the form of Military Ammo Bags that look like elongated duffel bags, or Military Duct Tape. The best locations it can be found in are Camp McClintock and Fort Defiance, but it can also be found in Abbie's Bunker, Camp Venture, Clancy Manor, the Converted Munitions Factory, Firebase LT, Firebase Major, Firebase Station Alpha, Firebase Station Delta, the Monongah Power Plant, the National Radio Astronomy Research Center, Sons of Dane Compound, Spruce Knob, the Thorn, and Watoga Civic Center.

You can also purchase Bulk Ballistic Fiber from the bot at Watoga Station, Raf at Crater, or Sunny at Foundation. Each Bulk Ballistic Fiber contains 10 Ballistic Fibers. It cannot be crafted, only purchased.