My 11 year old daughter wanted to be a Weeping Angel for Halloween. What could be scarier? I didn't want to have to do any sewing, and wanted it to be as cheap and easy as possible. We weren't too concerned with absolute stone-like accuracy, more with BEING JUST AMAZINGLY FREAKINGLY TERRIFYING AND AWESOME COOL.
The costume had to be warm, because it often snows in Colorado on Halloween. And we didn't want to have to paint too much of her body, because of the expense of the paint and because it gets itchy.
We started with a second hand choir robe as the base. Angel wings and werewolf teeth from a costume shop. Krylon "make it stone" paint in "black granite" (grey for the robe) and "obsidian" (black for the wings).
Step 1: Painting the costume
I made a rough sash out of a piece of black satin fabric we had lying around. Then we painted the robe and sash with the black granite "Make it Stone" spray paint.