Have a public drawing based on physical randomness, which is then videoed and broadcasted. For example, a ball bouncing around a chamber, where the floor of th

Have a public drawing based on physical randomness, which is then videoed and broadcasted. For example, a ball bouncing around a chamber, where the floor of the chamber is divided between contact pads representing different digits. Each time a ball bounces off a contact pad, add that pad's digit to a list, after X bounces concatenate the list to a seed value. In a perfect world, with a perfect launching mechanism, you may be able to predetermine which pads the ball will land on and thus guess the seed value ahead of time. But the world isn't perfect. Just give the ball to a four year old who doesn't understand the meaning or consequences of the ball launch, and let the kid throw it into the box.