Until VTK developers find the time to make VTK available on PyPI, you can use 3D Slicer’s Python environment, which comes with VTK 8.2 preinstalled. It is a standard Python-3.6.7 environment, so you can pip-install any additional packages you need. You don’t need to use Slicer application’s built-in Python console but you can use just a plain Python console. It is available for Windows, Linux, and Mac.