Anyway, while I was doing this I found a lot of really bad versions of it online, so I thought I'd share a few tips to get a nice light effect, as opposed to doing a flower that looks more like an exploded cabbage.
First, the edges of the petals have a little jagged edge to them, so don't make the petals totally round. I used peony petal cutters so that they'd have some movement.
Next, don't skimp on the petals! This cake was a 5-7-9-9", and it used about 150 petals. I did about 30 of the smallest petals, which were about 1 1/2" wide, then about 40 of slightly wider ones, 60 of the next widest ones, and about 20 of the largest ones. The length isn't as important as the width, since you'll be nesting them in behind the row in front of it and you'll probably need to break off the pointed ends to get them to fit anyway.
The most important part is to NOT paint too far into the edge of the petal. The color should be about 1/16th of an inch onto the edge, then you can drag it SLIGHTLY into the petal. If you paint a band that's even 1/4" thick it will look too thick and heavy when you put them all together.
This style of flower works best on cakes with about a 2" difference in diameter between tiers as opposed to a 3 or 4" difference. The more upright profile lends itself to the flower shape better than trying to fit it onto a more pyramid shape. The double-tall tier on the base lets you apply the flower on a flat surface and really spread it out for the wide look without having to adjust for different tier sizes.
The largest petals at the very edges of the flower are painted on the cake itself, not made of gumpaste. That will finish the design and visually flatten the flower out against the cake.
Kara Buntin owns A Cake To Remember LLC in Richmond VA, and cake supplies online at www.acaketoremember.com and www.acaketoremember.etsy.com