Elaborate in detail from four aspects: basic support structure, lining and filling, characteristic functional design, and detailed decoration. Material and craftsmanship for the design of the foundation support structure bed board: The bed board is usually made of high-quality wood that matches the coffin body, such as hard maple, red oak, etc., to ensure overall strength and stability. The bed board will be finely polished to a smooth surface, avoiding any scratching or discomfort to the deceased's body.  

Support method: Generally, multiple crossbeams are used to support the bed board, and the crossbeams are firmly connected to the coffin side walls through mortise and tenon structures or metal connectors to ensure that the bed board can withstand sufficient weight. Some high-end American wooden coffins will also have reinforcing ribs under the bed board to further enhance support.  

Bottom structure moisture-proof treatment: Considering that the coffin may be buried underground for a long time, the bottom structure will undergo special moisture-proof treatment. For example, applying waterproof paint or laying moisture-proof mats on the surface of wood to prevent underground moisture from entering the coffin and protect the body of the deceased.  

Breathable design: In order to maintain moderate air circulation inside the coffin and avoid odor or bacterial growth caused by moisture accumulation, some small breathable holes may be set at the bottom. These breathable holes are usually carefully designed to not affect the overall sealing of the coffin, but also ensure slow air exchange.