Design 5

The clock will now also be vertically mounted instead of lying on the floor, giving it a bit more of a clock-like vibe.

There's a 4RPM high-torque synchronous motor behind the sprocket. That little guy has 25 teeth to the full wheel's 100 teeth. The synchronous motor is immune to voltage fluctuations so it'll be at a regular and constant speed. They're not cheap though.