Robo Pen for Aground is a free mod designed for Windows that introduces a new structure to the game, enhancing resource management. This mod allows players to construct a Robo Pen, which can house up to three animals of any type. Once built, the Robo Pen automatically collects resources produced by the animals, streamlining gameplay and allowing players to focus on other activities. The blueprint for the Robo Pen can be acquired from the shady merchant located at Sunset Haven, making it accessible for players looking to optimize their resource collection.

The functionality of the Robo Pen varies depending on the island where it is located. When on the same island, the pen actively collects resources as they become available, while if placed on different islands, resources are pooled together based on the number of animals housed. This means that players can efficiently gather items like dragoonblood from multiple Robo Pens, enhancing their gaming experience and encouraging exploration across different islands.