This paper toy is Metal Gear REX, a Metal Gear prototype that was jointly developed by DARPA and ArmsTech for the United States Army in the early 2000s, based on the action-adventure stealth video game series Metal Gear, the papercraft is created by CubeFold.
Metal Gear REX is named after the Tyrannosaurus rex, due to its theropod-like design; other similarities include the open cockpit's resemblance to a gaping mouth, along with its ability to roar. The word Rex itself is Latin for "King," which was also the Allied codename used for the Japanese Kawanishi N1K floatplane during World War II.
Metal Gear REX is operated by a single pilot within a completely self-enclosed cockpit, shut off from the outside environment. The radome on REX's left arm houses multiple electronic sensors that are connected to a high tech virtual reality interface within the pilot's seat. Destruction of the radome, however, cuts off the sensory data feed and renders the VR interface inoperative, forcing the pilot to manually operate REX by opening the cockpit, which also exposed it to enemy fire. This flaw was deliberately engineered by Otacon during development, as he felt it wouldn't truly be complete without a weakness or "character flaw" of some sort.