code: def shrink(self, fraction=0.85):
          
          poly = self.polydata(True)
          shrink = vtk.vtkShrinkPolyData()
          shrink.SetInputData(poly)
          shrink.SetShrinkFactor(fraction)
          shrink.Update()
          return self.updateMesh(shrink.GetOutput())
docs: Shrink the triangle polydata in the representation of the input mesh.
  
          Example:
              .. code-block:: python
  
                  from vtkplotter import *
                  pot = load(datadir + 'shapes/teapot.vtk').shrink(0.75)
                  s = Sphere(r=0.2).pos(0,0,-0.5)
                  show(pot, s)
  
              |shrink| |shrink.py|_