Cabinet boxes are constructed from either plywood or particleboard (MDF-core or wood-composite) depending on the manufacturer and price tier. Plywood boxes are significantly stronger, hold screws better over time, are more moisture-resistant, and are the standard in quality semi-custom and custom cabinetry. Particleboard boxes cost less to produce and can perform adequately in dry interior locations, but are more vulnerable to moisture, lose screw-holding ability over time, and are generally found in entry-level stock cabinets. RainFire Builders specifies plywood box construction as the standard recommendation on all kitchen and bathroom cabinetry scopes — it is not a premium upgrade; it is the baseline for quality.