My daugther and I just finished this tonight and it turned our pretty good. We used a black plastic table cloth ($1.00) and some yellow tissue paper. Took some time to cut it out, but I was pleased with the results.
All I did was measure the window, and then cut the black plastic to fit. I then enlarged the stencils, taped them to the plastic, and cut right through the paper and plastic with an xacto knife. We then glued yellow tissue paper to the back and taped it up.
Here is a closeup