Write a manual and I'll read it. What you have doesn't give ANY of the assumptions in the particle engine, the render engine, fresnel terms...shall I go on? All of the underlying algorithms have to be worked out through experimentation, like old-time atomic structure experimenters firing electrons in and seeing which direction they bounce. The "manual" is simply a laundry-list of the names of buttons, a slightly tutorial-like slant where you are told which button to press for a specific effect....oh, and maybe 30% by weight cross-references (including cross references that point from the bottom of a paragraph back to the top!) ((If I thought anyone cared I'd send in a page of typos, misspellings, and broken cross-references.)) Oddly enough, you CAN create something a lot like a ripple. I did it and made an animation. Actually, it was a bit more like a lumpy splash, but the idea was there. All you have to do is add the object you are dropping to the collisions. My render was not high enough granularity, however, to see if I was actually pushing particles, or if my "dropping" object was acting as a deflector to the still-operating particle fountain. And thus I have a very specific question; Do particles self-collide, and if so, what determines the collision radius?