This gundam paper model is a SD RX-78-1 Prototype Gundam, a prototype general purpose mobile suit and predecessor to the RX-78-2 Gundam, the papercraft is created by shirokumakoubou, and shared by Ziyi.
The RX-78-1 Prototype Gundam is the third Mobile Suit produced under the Project V, developed at the Jaburo military headquarters on Earth. The starting point of the RX-78 series of mobile suits, the Prototype Gundam was designed differently from the original Project V mobile suits models in that it did not place its emphasis on raw firepower like the RX-75-4 Guntank and RX-77-2 Guncannon. Instead, the RX-78-1 placed emphasis on fast, close quarters combat, much like the Principality of Zeon's MS-06 Zaku II. It was also the first to feature several new technologies, including the energy cap-based beam rifle a beam saber and a beam javelin for close quarters. Like its predecessors, the Prototype Gundam also featured the Core Block System and the FF-X5 Prototype Core Fighter.
Once the RX-78-1 was tested and approved for continued development, designs were upgraded and enhanced, eventually producing the second - and most famous model of the RX-78 series: the RX-78-2 Gundam. [Source: wikia]
You can download this gundam paper model here: