Has anyone ever made any ostrich feathers out of gun paste or fondant? I have a client that wants an ostrich cake, and I can't figure out how to make realistic looking feathers. Any ideas?

I'm not sure whether you would use gumpaste, fondant or a mix of the two (if I were doing it, I would use the 50/50 mixture), but here's the link to a really cute peacock cake I saw on here the other day, in case that would give you some inspiration (not sure what ostrich feathers look like, sorry!):
http://cakecentral.com/gallery/1968722

The only time I use gumpaste is if I need something thin to stand up on its own, like a petal on a flower or butterfly wings or something like that. The benefit of gumpaste is that you can roll it really thin and it dries hard and fast, so you can shape it and you don't have to prop it up or hold it too long before it's set in its shape.

I use 50/50 for things that don't need to be so thin, need some stability and need to set up firmly, but require a longer time to dry as they need to be worked on more. It's ideal for working on figures because you can work on expressions, fitting parts together, etc, before they become too hard on the outside.

I personally wouldn't use either of these on anything that would be covering a cake, such as feathers. You can get them thin enough with plain fondant. I can't think of any reason to add gumpaste as you don't need any stiffness as they'd be lying flat. And layers of gumpaste or 50/50 feathers covering a cake would make the cake difficult to cut and serve.

I'd find a leaf or petal cutter that looks kind of like an ostrich feather, maybe a magnolia petal cutter or even a peony cutter. Cut out of thinly rolled fondant. Then use a petal veiner to give it some texture, or just use a sharp tool to make some feather texture marks in them, then lay them in overlapping rows. Do it like you see theater seats, rows staggered so that the feathers line up between two of the feathers in the row in front of it...if that makes sense.

I'm usually at a loss as to which of all these things to use, so thanks for breaking it down, artscallion. And I know what you mean about "marshmallows", hahaha!