How do you make a odometer?

To make a basic odometer, you can use a rotary encoder or a gear mechanism connected to a wheel. As the wheel turns, the encoder or gears count the rotations and convert this into distance traveled based on the wheel's circumference. This data can be processed using a microcontroller to display the distance on a screen or through a mechanical dial. Ensure to calibrate the device for accuracy by measuring the actual distance traveled against the readings.