The Art Nouveau window was done with Crystal Gel.
First, we made a pounce with brown paper and pounced it onto a starched canvas. Then we markered all the lines in the design. Next, Crystal Gel was tinted with Supersat paint, Faux Creme Color (by Faux Effects) and food coloring. Colored Crystal Gel was applied with old hotel key cards to give a textured glass effect. Last, Crystal Gel tinted heavily with black Supersat paint was piped on with a baggie. (I think, however, that an actual cake froster with a tip would have been easier to control)