As I’ve been learning Blender over the past little while, I have a distinct memory of playing with “free-form extruding” of edges. It was very easy to select an edge and then freely extrude it forward on the plane I was on (in top view, for example). The freedom was in the fact that I could easily rotate the extruded edge. Within seconds I had created a curvy mesh. It felt almost like “painting” the extrusions. At the time I thought “cool, I’ll come back to this”.
Now I’ve forgotten how I did it. Was I using an addon? All I’m able to do right now is use the regular Extrude command. This means I can only rotate the new edge after, and have to constrain the rotation as usual.