code: def lipid_box(self):
          
          if self._lipid_box:
              return self._lipid_box
          else:
              self._lipid_box = self.lipid_components.boundingbox
              # Add buffer around lipid box.
              self._lipid_box.mins -= np.array([0.5*np.sqrt(self.apl),
                                                0.5*np.sqrt(self.apl),
                                                0.5*np.sqrt(self.apl)])
              self._lipid_box.maxs += np.array([0.5*np.sqrt(self.apl),
                                                0.5*np.sqrt(self.apl),
                                                0.5*np.sqrt(self.apl)])
              return self._lipid_box
docs: The box containing all of the lipids.