This is a SD type tank papercraft from the game "Advance Wars", this tank paper model is designed by ninjatoes. Megatanks (known as Gigatanks or War Tanks in some versions) are a land unit introduced in Advance Wars: Dual Strike, replacing the Neotank as the most powerful land unit. Although strong, they are very slow and use up a lot of fuel very quickly. Their weapon, the megacannon, is very potent and can seriously damage most land units. They were designed by Green Earth in Dual Strike, and soon become available to the Allied Nation after it debuted in a test battle against Orange Star by Jess and Javier.
You can download this tank paper craft from here: Advance Wars - Black Hole's Megatank Free Paper Craft Download