Slide the mat to the left until it rests halfway under the vertical clamp (do not push it all the way under the clamp). Engage the clamps.
Cut opening as usual, from the back, opening only and face down.
Draw a small X in the bottom left side of the fallout before you remove the mat from the fallout.
Open the clamps and remove the one inch mat from the fallout.
Position the fallout so the left side of the fallout is about 1” away from the vertical clamp. Draw a pencil line down the right side of the fallout, top to bottom