Visual Studio Community 2015 suffices to build extensions for Python 3.5. It's free but a 6 GB download (overkill). On my computer it installed vcvarsall at C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat
For Python 3.4 you'd need Visual Studio 2010. I don't think there's any free edition. See https://matthew-brett.github.io/pydagogue/python_msvc.html