Fallout 76 junk items

General information
Similar to Fallout 4, junk in Fallout 76 is collected and used primarily for the crafting of workshop objects and equipment mods. New to Fallout 76 is the ability to craft armor and weapons from scratch using junk and plans. Junk can also be used to repair C.A.M.P.s, workshops, and equipment. Several Intelligence perks reduce the amount of junk needed to repair objects and items, while others reduce crafting costs. The Pack Rat perk can reduce weight of junk items by 25/50/75% and the reduced junk weight legendary effect can reduce weight by 20% per equipped armor part, with a maximum of 90% reduction.

Crafting components
All junk items can be scrapped to yield one or more components at any workbench. Components, or scrap, weigh less than junk and may be stored in the Scrapbox. The "scrap all junk" option available at workbenches will scrap all junk items in the inventory automatically, with certain exceptions.

Components
The following items may be stored within the Scrapbox ( only):  

Bulk
Raw crafting components can be turned into bulk versions at a tinker's workbench. This costs a set number of the involved components to be bulked plus two plastic to wrap it. The only two components which experience a weight reduction when bulked are aluminum (the bulked version is 0.5 lighter) and lead (the bulked version is 1.0 lighter). Although bulking plastic appears to result in a net weight reduction, this is due to the consumption of 2 plastic in the bulking process. The resultant bulked 10 plastic weighs the same as 10 loose pieces of molded plastic.

In addition to weight reduction, bulking certain crafting components will allow them to be sold to in-game merchants. Merchants will not purchase the individual versions of any crafting component which can be bulked. Some bulked components can only be purchased from merchants. They cannot be crafted by the player character at a tinker's workbench.

Component sources
Scrap components and their sources:

Junk items
