If you wanted an object to rotate parametrically within a family, most Revit blogs and forums tell you to use a reference line. They also usually state, “do not use a reference plane,” with various reasons, mainly being that you can’t control how they rotate. Well, I’m here to tell you that is simply not true. Not only can you easily control a rotating reference plane, I find it can be easier to host and rotate sweeps along a plane (rather than a line).
To start off, draw a plane at an angle, and give it a parameter to flex. Modify the angle.