Final answer:
A firm material called lauan placed on a wooden or hollow metal frame, which can be painted and have three-dimensional plastic moldings attached to it to create cornices, chair rails, and other features, is called a hard-cover flat.
Step-by-step explanation:
The firm material called lauan placed on a wooden or hollow metal frame, which can be painted and have three-dimensional plastic moldings attached to it to create cornices, chair rails, and other features, is called a hard-cover flat. This term refers to a rigid structure made of slender pieces joined together to surround sizable empty spaces or nonstructural panels, commonly used in building or engineering works, furniture, etc.