This Mario papercraft is Goomba, Goombas are one of the major species of Mushroom World and are among Mario and Luigi's most persistent foes, the paper model was created by icthus7. The finished model stands about 12 cm. There is another paper model version on the site: Super Smash Bros. Brawl - Goomba Free Papercraft.
Since their first game appearance in Super Mario Bros., they have appeared as a common foe. Goombas resemble small, brown mushrooms and are a fungus-based species like Toads, Amanitas, Spooks, and Shroobs. Goombas are physically weak and are not much of a threat to Mario, since a single stomp usually defeats them, although a number of different Goomba sub-species have emerged throughout the years. The Goombas, as a collective race, used to be allied with the Mushroom Kingdom. However, many of the Goombas have turned traitorous and joined the Koopa Troop, an organization led by Bowser.
However, not all Goombas are allied with Bowser or the Koopa Troop. Some Goombas, such as the inhabitants of Goomba Village, live peacefully inside the borders of the Mushroom Kingdom, while others simply hold no allegiance and operate independently in distant locales such as Rogueport and Monstro Town. [Source: Mariowiki]
You can download this mario paper craft model here: Super Mario Bros. - Goomba Free Papercraft Download