I started out with the marbles being quite organized on a disc, and then tried to get  some DOF, and a little bit different shot, and then I dumped them all together and took some shotsto see what happened.  After that I added  some pebbles and this is the end.  Before I started, I had to hunt all over the house to find where my grandkids had hidden the marbles.  It is frustrating when you have an idea and can't find the stuff.