ooooh, lovely! I adore the variation of textures in the scales. It looks like someone used a circle cutter to cut circles out of the fondant (or gumpaste), used the same circle cutter to cut out the divets and create the point of each scale, and brushed some scales with disco dust, some with luster dust, and left some plain. And then stuck them on the side of the cake, one by one.
Either that or make a template (it is actually a patchwork pattern) and cut around it with a scalpel.
Any idea where to find that patchwork cutter?
I would take a small round aluminum cookie cutter and bend it to that shape.
I don't know if this would help, but when I saw the cake picture, I recognized a Japanese sashiko quilting pattern. There are templates in that design on this page:
1. The top row, the one in the middle
2. In row 4, the one on the right.
Perhaps you could roll out the fondant, mark the design through the stencil, and then cut on the marked lines.
Also on this page:
W1001 - Clamshell (about halfway down the page)
That IS a stunning cake...good luck re-creating it. I might try to do the same!
I would measure out the top of the cake so you know how big you can go? Then measure cookie cutters to find one that will work. Then brace yourself...cut it in half.
That way you have the same pressure on each arc and you don't go too far into your cake trying to avoid the whole cutter. Then mark very slightly with a toothpick all the way around the cake the size..every inch ect.
After you have the top row done you can pretty much eye ball it from there on down.
This cutter set from a seller on FB should help: https://www.facebook.com/photo.php?fbid=531918050178716&set=pb.161658887204636.-2207520000.1372565354.&type=3&theater
The only problem is her stuff is ALWAYS sold out, she posts on her page when her next sale date is, and everyone clamors...