Get The Perimeter Curve of Solids by Union

I have alot of Solids Framings and Footings and i union them in one Solid i want to get the Perimeter Curves of them like This 01 02

Two options come to mind:

  1. Intersect with a plane where you want the curves to be pulled from.

  2. Topology.Edges > Edge.CurveGeometry > Curve.PullOntoPlane.