As you know in The Division 2 there is the possibility of creating paraphernalia using recycled materials. Among these is the Printer Filament , a material that is used to create mods for tools and skills. This is a rare purple-tier item, so rare, but it's also hard to find. In fact, you will not be able to find it normally in the game world by opening boxes and crates, but the only way to get it is by dismantling the objects deposited in your inventory.
The first thing to do is to reach Level 10 to unlock the Skill mod. Then as you play you will accumulate various weapons, armor and mostly useless items. Even if money is always handy, wait to give it to the seller immediately but dismantle it to obtain other accessories that will be used to produce better armaments. Unmounting them is simple: open the main menu, select the Character option, choose the category that contains the object you don't need, select the thing you want to unmount and press and hold R3 / RT.
There is also another option. At the Quartermaster Base of Operations, if you unlock the Deconstruct 2 bonus, you can get a rare item every time you dismantle an item.