How do you do them? Are they just gumpaste rolled out/cut/left out to dry?

I.e. doing a cake in the form of a "present" with a little name card sticking out by the bow to say "happy birthday" or something, that's the plaque I'm talking about.

Yup. Pretty much. You could also use fondant.

I've used fondant with some tylose powder mixed in and also just plain gumpaste.

I used fondant and let it dry a bit then added the writting with food markers and it turned out ok.

I almost always use fondant. Just roll it out pretty thin and smooth and viola!

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