I have noticed a lot of tiara's in photos on here. Most say they used royal icing. I have never used royal icing, can you pipe it on a stencil and then after it dries pick it up and shape it? If not what would I need to use to be able to do that?
With royal, you can pipe it but it you have to place it in the shape you want it to dry in and always make extra.
the other alternative is to use fondant, but you still have to dry it in the shape you want it to be in.
Whether you're using royal or gum paste, you want to use something that is rounded - my favorite for tiaras is taping a template onto a oatmeal canister and going from there. There are many threads that discuss the how-to's of making tiaras. Here's a good one for royal icing tiaras - http://cakecentral.com/articles/129/how-to-make-a-royal-icing-tiara