Rotational Model Mechanism Design

I have an architectural model that needs a simple, reliable rotational motion added to it—nothing fancy, just smooth, continuous movement so the concept can turn on display. The priority is basic functional movement

You can consider any basic dimensions. We just need to do a POC for future projects.

• A compact rotational mechanism concept that fits the given envelope
• CAD files (STEP or similar) and clear assembly drawings
• A concise parts list with readily available components

My main concern is the belt, The magnet element, motor is Nema17 fixed the mechanism should be easily replicate for future display