The view of the structure in the horizontal optical axis front to back.
The box is made of ABS of good quality and thermal resistance of at least 100 degrees Celsius.
For RF shielding reasons it is designed with the grounding levels as shown in the picture.
The entire surface of the two lids is covered internally with a shield connected to the computer ground (not the P/D - it has a separate ground).
The main board is double-sided and apart from its active lines for the circuit, the rest of the surface is a shield surface with multiple top and bottom via connections. A small piece of this double surface around the 5-pin connection to the P/D is independent from the rest and belongs to the grounding of the P/D.
All the surfaces connected to the respective grounds of the front and back sides create in the closed box a Faraday cage.
(Drawing sizes are indicative and not scaled)