code: def mergeActors(actors, tol=0):
      
      polylns = vtk.vtkAppendPolyData()
      for a in actors:
          polylns.AddInputData(a.polydata())
      polylns.Update()
      pd = polylns.GetOutput()
      return Actor(pd)
docs: Build a new actor formed by the fusion of the polydatas of input objects.
      Similar to Assembly, but in this case the input objects become a single mesh.
  
      .. hint:: |thinplate_grid| |thinplate_grid.py|_