True random number generation is hard, but nature can help! This project uses the unpredictability of wind to increase randomness.

How it works: the wind blows and spin the turbine, which spins magnets surrounding a Hall Effect sensor. The sensor's analog reading is then used to seed Arduino's random number generator.

In this project, I demonstrate how it works using an Arduino Leonardo with LCD shield to display both the sensor reading and the generated random numbers.

 

Parts List

• Arduino + Mounting Hardware + LCD Shield by DFRobot + 9V Battery with Connector.
• Hall Effect Sensor + Wire.
• 4 Magnets (1/4" diameter cylinder. 1/16" thick).
• 2" T-pins (it's the axle).
• BB gun ammo, Stainless Steel, 4.5 mm (balls for bearing).
• For enclosure: #6 machine screw

Easy to make; no soldering. No print support. Any dimensional correct printer setting would do. The only overhang is screw mounting holes, which you tap out. The rest of the overhangs are no larger than 45 degrees. Many parts are friction fitted.

Source:Thingiverse