Add Top Wall Modifiers

Enables you to change the top height of a wall by trimming or extending it to a single-line object.
The object can be a line, arc, or polyline. It must be at least as long as the wall, and cannot extend below the bottom of the wall. In addition, it must lie in the same workplane as the wall.

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If you add another Top modifier, it will cancel the effect of the previous one.