Ok, to be fair it’s not “functional” in that it shoots an actual laser projectile, but the barrels (if you can call them that) spin, the muzzle flashes with light, and it makes game-authentic sounds.
If you have the aptitude necessary to make one for yourself, the creator put the plans online here:
www.myminifactory.com/object/fallout-4-automatic-laser-rifle-25153
This looks cool!
But can you modify it like in fallout 4? lol