Toms Segli?š shares his Maya script “Edges to Curves” which will create Curves from selected objects without too much trouble. Maya already has the ability to create curves from selected edges, however, as Toms notes, it can’t really create or convert curves on multiple selected objects.
Why? Because maya cant convert multiple object selected edges to curves…
Edges to Curves is a a little python script that will present a simple interface that will allow you to bake the edges that you wish to create into curves, a make curves button to actually create them once baked, and a loft curves button that will perform a loft operation creating an object from the curve. Check out the Edges to Curves script for Maya here.