This 3D printed part covers te rear of the ping sensor module and attaches to the back of the robot face. It is held in place with two No 4 screws. It has a notch on the bottom to allow the cable to exit. The slots are for ventilation, however I doubt hardly any heat is generated.
You can download the .stl or Freecad files here;
Don't have a 3D printer? If you are in the UK you cano order one from civrays via makexyz.
Please check out the other 3D parts;