Evan Abrams dives into creating randomization by using expressions with various attributes in After Effects.
Likely the only practical way to create a random thing is through an expression engine, and in Adobe After Effects, a couple of simple lines will get you pretty far. Check out this new tutorial from Evan Abrams that shows some more refined details for creating randomization in Ae.
“We’ll explore the main methods and functions in this introduction to random expressions in After Effects.” The tutorial also covers a few ways that you can use to control, clamp, and refine randomness and a few ways to use or deploy randomness in properties to get you thinking about the possibilities.