You have to acquire an ISO in some legal way yourself. Then, you can use something like packer-windows which has pre-built templates for various versions of Windows to build Vagrant-compatible boxes in about 10 minutes: https://github.com/joefitzgerald/packer-windows
It isn't as easy as "download pre-built Linux box" but for environments that are using Windows, this workflow has been amazing for them above what they used to do, and is quite fast.
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You have to acquire an ISO in some legal way yourself. Then, you can use something like packer-windows which has pre-built templates for various versions of Windows to build Vagrant-compatible boxes in about 10 minutes: https://github.com/joefitzgerald/packer-windows
It isn't as easy as "download pre-built Linux box" but for environments that are using Windows, this workflow has been amazing for them above what they used to do, and is quite fast.
Thanks, I'm going to give this a look since you can use the trial ISO's.