Simple 45 degree louver to redirect air from a 120mm fan, which can help with airflow if the computer sits right in front of a wall. Can be mounted in all four directions so you can point the exhaust wherever you want. In addition, it helps cut down on LED bleed out the back of the case without impacting airflow. Was specifically designed for a Fractal Meshify 2 Mini case, which has the fan grill offset by around 3mm from where the screws are, so there are feet so that it can be mounted flush. It's not a structural part and doesn't take load, so it can be printed with minimal walls and infill.
The author marked this model as their own original creation.