Test ❶: Can you modify brick or plastic with an adjective that applies only to them not to some noun that follows them? When you have a fake brick house, the house is real but the brick is fake, so the brick can only be an attributive noun there. Test ❷: Can you use these prospective adjectives predicatively, not just attributively? If those are predicate adjectives, then the bridge is steel, the spoon is plastic, the house is brick “should” (necessary ʙᴜᴛ ɴᴏᴛ sufficient) all read ok. Yet the bridge is stainless steel, the spoon is crumbling plastic, the house is fake brick disproves. — tchrist ♦ 1 min ago