This paper model is a Type 90 Mobile Maser Cannon, a fictional weapon featured in many of Toho Studio's sci-fi and fantasy films, for example, Godzilla Against Mechagodzilla, the papercraft created by SF Papercraft.
One of the many military weapons in the arsenal of the Japanese Self-Defense Force, the Type 90 Maser Cannon was utilized during an epic battle with Godzilla in the mid-1960s. The snow and ice of the Antarctic landscape gave way to these technological wonders as they made their approach toward Godzilla. The searing streams of electricity fired, and along with a wide variety of other military weaponry and a brutal storm, it appeared as though the advantage was immediately on the side of the humans. Shortly after the assault commenced, however, the wretched reptile began to regain his composure and retaliate. Among his primary targets were these devices that inflicted pain and agony in their flowing currents, and it did not take long for a single atomic ray to wipe out the maser resistance.
Following in a line of effective maser weapons, the Type 90, which shares similarities in such things such as design with the earlier Type 66 Maser Cannon, was one of the most powerful weapons in the arsenal of the Japanese Self Defense Forces. Unfortunately, it did have a few weaknesses with the most important being that if it had to fight against a kaiju in a rainstorm, the rain would reduce the power of the energy beam.
Eventually they met their match in 1999 at the hands of Godzilla who easily destroyed the Type 90s maser cannons during a battle around Tateyama. Their ineffectiveness persuaded the Japanese Prime Minister at the time, Machiko Tsuge, to sanction the development of new weapons, including one that used the bones of the original Godzilla as its basis. Despite the weapon's ineffectiveness against Godzilla, the Type 90 maser cannon continued to see action in subsequent battles against the king of the monsters.
You can download this papercraft model here: Type 90 Mobile Maser Cannon Free Paper Model Download