If you don’t know how to use it this is how (on console) you need to press square on PS and on XBOX press X hope this helped I also struggled with it once 😊
Laser Attachment
This advanced aiming device places a red dot where the weapon is pointed. Attach this to a supporting weapon to add a laser sight. Supports: Pistols, Assault Rifle, Shotguns, Longneck Rifle, Sniper Rifle.
Recipe
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To make Laser Attachment, combine Metal Ingot, Crystal, and Electronics in a Fabricator for 10 seconds. The Laser Attachment unlocks at level 59 and requires 24 Engram Points.