For testing purposes we start with a triangle. We get this from 3 edges of a simplex node. The simplex is a tetraedron. We make the size of the edges about 100.
From the shape of the tetraedron we extract an edges using the edge node with index 0. This is simply Edge1 of the shape.
Using the discretize node we split the edge/line into 20 segments.
In a next step some randomness is added to this polygon to get a nonlinear chain. The resulting points are used as poles for a BSpline curve.
We repeat the same workflow for Edge2 and Edge3 and join the resulting curves into the Shape_in of the conny node.
Creating a preview of the tetraedron and the conny face we get the result. The conny face is a modified face of the base face of the tetraedron.
the red curves are the bspline curves.