Next, it was time to begin laying out the chop. I wanted to keep the bottom of hte rear window opening at the same height, therefore I decided to take the chop out of the lower B-pillar and leave the window opening alone. To do this, I measured 2 3/4-inch down from the bottom of the opening and laid a piece of horizontal masking tape around the B-pillar and through the doorjamb evenly. A level helped out in that step. Once finished, I transferred my layout to the other side.