Sorry I haven't answered questions recently. The last few days I've been out with Bronchitis. I've got an image of the car with the plug. The plug is the original piece from which we make the mold off of. The lines are a little bit thicker on the plug. This is done so that when the reverse (mold) is made and production piece from that is created the result will come out thinner.

I've uploaded the image for you to see on an actual car, so keep in mind that the curvatures and thickness are not accurate of the finished product.