This is Destiny’s MIDA Multi-tool Scout Rifle. Elliott Feldman spent a few months building it, and he’s done a hell of a job.
I like two things in particular: the small details (like a removable clip and sliding trigger mechanism) and the fact he laughed at the notion of doing the normal LEGO builder thing (taking some photos and putting them on Flickr) and took it out into the desert to shoot a video about it.
(via Brothers Brick)