OpenVPN was split into several subprojects between 2.3-alpha1 -> 2.3-alpha2 releases. Openvpn-build was written from scratch and it replaced earlier "domake-win" and Python-based MSVC buildsystems.
Fetching openvpn-build using Git
Openvpn-build Git repos are available on GitHub. To fetch the sources, use
$ git clone https://github.com/OpenVPN/openvpn-build.git
Getting openvpn-build releases
At the moment there are no openvpn-build releases.