These mecha paper models are Hot Dog Knights, a group of canine-like hot dog creatures that first appear in "The Limit", based on the American animated television series Adventure Time, the papercraft is created by WebDude.
They typically wear medieval helmets and wield various weapons such as swords, hand-axes, and maces. Their ruler is Hot Dog Princess.
A team of Hot Dog Knights was lost in the Labyrinth and more Hot Dog Knights were sent to rescue them, but they also got lost. Hot Dog Princess sent Finn and Jake to recover them because she explained that the knights are very dumb and are unable to take care of themselves.
They found four of them near the entrance to the labyrinth, likely meant to emphasize how "slow" they are. One of the Hot Dog Knights then informs Finn and Jake of the reward for reaching the center of the labyrinth: a wish. The heroes then decide that they will find the end of the labyrinth before focusing on the rescue mission, and they simply bring the Hot Dog Knights with them. Two of the Hot Dog Knights are killed at the end of it.
Of the other two, one is left in the room prior to the end of the labyrinth and the other wishes for a box and is quite pleased. They are later resurrected when the Ancient Psychic Tandem War Elephant wishes for Finn's friends to be healed. The Hot Dog Knights are much smaller than Hot Dog Princess, and are bipedal instead of quadrupedal. There are at least six hot dog knights and it appears that one of the hot dog knights like kittens. [Source: wikia]
You can download the papercraft template here: Adventure Time - Hot Dog Knights Free Papercrafts Download