I don't recall seeing it here but I've done one that you stack up nine squares and cut across once randomly. Take one piece from the bottom and put it on top. Now slice again randomly. Take one piece from the bottom and put it on top. Slice again. I think you do this 4 times in order to get 9 different pieces. The pattern I have says to rejoin every time you cut but I think you can cut all at one time, provided you don't get your layers mixed up! Be sure to remember that seam allowances need to come off of your pieces so give yourself room for those when you decide where to slice.
I haven't looked for this pattern online but it's called a Crazy 9 Patch and is similar to stack and whack.