Industry 4.0 marketing loves the words digital twin. Building one for a smart classroom lab taught me what that actually costs: mechanical truth in CAD, mesh cleanup for realtime, Unity logic tied to device IDs, and VR review before anyone touches physical equipment.
Factories and teaching labs share the same integration pain. A temperature tag on a 3D model is useless if it is not bound to the same identifier the edge node publishes. We copied that discipline from field IoT work — simulated JSON first, then real MQTT when the hardware was ready.
The twin is not a pretty screenshot. It is a contract between mechanical layout, software state, and operator training. Normal, alert, and fault scenarios forced us to think like a line supervisor, not like a demo presenter.
Smart factory skills I am deliberately practicing: multi-tool pipelines with clear handoffs, performance budgets for immersive clients, and documentation so the next student or engineer can extend the twin without reverse-engineering the scene.