Apply the liquid lead following the traced lines of your design.
If your lamp shade design doesn't end in a straight edge, then let the liquid lead dry in the rest of the design, and cut the shape of the edge of the lamp shade following the figures in the edge. Then apply the liquid lead to the edge.
Please take note that, apart from high-tech adhesives for PET, nothing sticks to it. So we are creating a shell on top of the PET. If after the liquid lead is dry, apply some more on the back side of the edge.