Michael
The array along curve with normals to surface is a wonderful idea. I feel that at this juncture, perhaps, it is prudent to look ahead a little. The next step, of course, is to add prongs into the mix. Because, after you get the stones where you want them...your going to need prongs to hold them in place. This brings up a whole different set of parameters as well as problems. Perhaps the simplest way to achieve adding the prongs into the equation, while taking into consideration the necessary spacing requirements, would be to add the prongs to a stone, group it, and array the prongs and the stones at the same time. This of course assumes that the stones and the prongs are consistent in size. If not, it leads down the road of necessitating sliders or multiple check boxes or places to designate specific stone sizes within the array to change the shape and size and distance between the stones either pre or post applying them to the surface. (that was a long winded sentence but hopefully you can grasp the entire concept) Pave' is the ultimate test...and nightmare. Overlapping stones and prongs must be found and eliminated, or some type of system that the program arranges the stone placement in the most exacting and specific manner must be designed and implemented.

David