If you are looking for the actual file or the specific text instructions contained within it, you would need to download it directly from the Banana Pi Forum post where the designer shared it. 7z archive ?
In the context of the Case design for the BPI-R4 thread, this file typically contains: grill.7z
: It is part of a cooling-focused modification intended to improve airflow over the internal components (like the NIC card and heat sink) without adding excessive height to the unit. If you are looking for the actual file
: Specifically .STL or .STEP files for the "grill" or ventilation cover of the router case. grill.7z