The models should at least reflect the size, shape, and articulation (flip covers and so on) of the device, and they are more effective when weight is also taken into account.

• 这样的物理模型至少要能够反映出该设备的真实尺寸、形状及连接形式（比如翻盖和滑盖等），重量最好也要差不多一样的。