I live in the tropics and I got tired of even my stiffest gumpaste wilting after a while, so I thought I'd try pastillage. My first attempt was a dismal failure - I waited too long to use it (days as opposed to hours) and I tinted it with water-based coloring, having skipped over the part of the recipe that said not to do that. And black no less, so I used LOTS of coloring. But I decided to try again for another cake and it was wonderful! I cut some extra pieces to experiment on, too. I tinted these with candy colorings (too light for what I needed) then I sprayed them with Wilton Color Mist colors (not enough variety for what I wanted) and I finally painted them with luster dusts dissolved in alcohol and got what I wanted. But the interesting thing is that ALL these coloring methods worked great and didn't weaken the pastillage. The only problem with this stuff is that it's not particularly sculptable (or if it is, would somebody please let me know how to do it?). I rolled it out flat and cut some shapes and I can see it working in a cornstarch-dusted mold. But the nice thing is that once it's dry, it's hard as a rock. So, okay, my peonies will still wilt at an outdoor function, but any beach chairs, tables and other things that can be cut out of flat pieces will be MINE to do with as I please - mwahaha!
Love pastillage for "architectural" things and I'm not even in the tropics.
I've never tried making flowers, but it can be done:
http://www.historicfood.com/events2008-9.html (near the bottom of the page). The pastillage dries quickly, so you have to be fast.
True pastillage is basically edible concrete and is really well suited to architectural elements. It's amazingly strong but lightweight.
You really can't make thin, fine "fussy" things out of it. It can't be "ruffled" and when thin, bends tend to fracture very easily.
I really doubt that those flowers are made from true pastillage. Terms are often used in other countries/other ways that aren't always completely accurate. I'd say that they're likely what we call gum paste (in the UK is flower paste), or they may be a hybrid (haha) like mexican paste (sort of gum paste & pastillage mixed together).
You can do finer work with mexican paste and it's more resistant to humidity, but you have to work faster than with gum paste.
Of course, you're right, Rae (as usual ). I just found a web page that defined pastillage as gum paste. Ha! I know that real pastillage can be sanded and probably drilled (carefully). Now, where are those power tools.....