This papercraft is the King Slime, a recurring monster in the Dragon Quest game series, the paper model created by Hellsword. Introduced in Dragon Quest IV, it is a giant, chubby, crown-wearing slime. In Dragon Quest VIII, it is called Slime Creator.
King slimes appear to be large, engorged slimes, notably due to their chubby cheeks imposing on the edges of their toothless grins. Going along with their kingly status, they have crowns, usually shown as being gold-rimmed with purple and green striped fabric.
In terms of strength, king slimes are a massive step up from the average slime in all parameters, especially HP and attack strength. They are often shown as being versed in magic, normally having Zing as one of the spells in their arsenal, meaning that they can be more than just a physical force. While king slimes can appear as is, players will normally first encounter this monster upon running into a group of special slimes that can summon others of their type; when eight of these slimes gather, they can pile up and fuse into a single king slime.
You can download this papercraft model here: Dragon Quest - King Slime Free Papercraft Download