I would like to know if there is a possibility to convert or fill the surface mesh STL/VTK/OBJ to a volumetric VTK file in paraview (pvpython). As it is possible to extract surface mesh from volumetric VTKs, is the reverse process straight forward.
@justAPhDStudent if your surface is manifold, you may use tetWild to fill it. This kind of operation should be done with a mesher. Using only VTK, I do not see any clean way to do so.