We have a containerized build system for 64-bit Windows based on Docker.

https://github.com/jcupitt/build-win64

All you need to do is:

$ sudo apt-get install docker.io
$ sudo ./build.sh 8.5

See the README for some more notes.

nip2 is still a 32-bit program for now. There's a slightly more manual build system for it here:

https://github.com/jcupitt/build-win32