Final answer:
The outer case of the M18A1 Claymore mine is made of a plastic material such as polycarbonate, designed for lightness and durability.
Step-by-step explanation:
The outer case of the M18A1 Claymore mine is constructed primarily of a plastic material, specifically a moldable plastic like polycarbonate. This plastic casing is designed to be light, durable, and capable of holding a specific curved shape to direct the blast of its steel ball shrapnel outwards.
The design allows the mine to be easily transported and positioned by soldiers in the field. The front face of the Claymore is also typically stamped with instructions and a simple sight to aid in deployment, with the words "Front Toward Enemy" famously instructing the user on how to orient the device.