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Note: The way to assign height to a wall is to open its Properties to the 3D page and enter a Height.
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1. Set the workplane to the wall you want to modify. The easiest tool is By Facet.
2. Create the object you want to use as a modifier. Be sure that the object meets or extends past the wall ends.
3. Activate Add Top Wall Modifier, select the wall to modify, and select the 2D modifier. The wall is trimmed or extended to meet the modifier.
The results may be easier to see in Hidden Line mode.
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