I created a stencil with plastic sheet from the art store, drawing out the pattern and cutting it with an exacto knife. I used spray adhesive to stick it to the wall and rolled paint over it. Eventually I had to cut the stencil to complete the top portion of the wall. After each section was complete I went back over the entire mural by hand, smoothing edges and correcting imperfections. It was quite a feat over a stairwell!