How to emit real random particles I'm working on a sort of idea that you can make an unique 'drawing' by downloading this blendfile, run the animation and get a truely unique drawing. Key of the concept is that designing needs no skill or knowledge.

Problem: I created a 'drawing machine' that emits random particles (size and life) and paints the canvas by using dynamic paint. But everytime I play the animation the exact same drawing comes out. 

Of course I could use seed, but it will contradict the concept.
You can use Drivers to get "random" Seed in Particles settings.


  As @Crantisz pointed you can just paste #int( 99 * noise.random() )
  as a Seed value and Driver will be automatically added.


Long way:


Right click on Seed and Add Driver > Manually Create Later (Single).
Go to Graph Editor and switch to Drivers mode.
In Drivers tab paste this expression: int( 99 * noise.random() )
Update Dependencies.


Now every time you open Blender Seed value will be different.