Some aspects of this remodel project have been intimidating since they involve skills I don't have, or techniques I've either never tried, or seldom get to use. Even worse when the results will be prominently displayed when the project is finished. The wainscoting on the stairwell presented one of those challenges.
Harbor Freight Multipurpose Angle Finder isn't terribly accurate due to its size, but since it is based on a four-bar linkage, it's actually pretty versatile beyond the simple application I employed it for. In my case I placed the tool in the angle between the stringer and vertical stile at the bottom of the staircase since that was the angle I wanted to duplicate on the other stiles. I checked the stile for plumb and was reassured that it was true enough to ensure the other stiles parallel to it would also be plumb.