$ packer build -only=virtualbox-iso --force windows_10.json
virtualbox-iso output will be in this color.
==> virtualbox-iso: Downloading or copying ISO
==> virtualbox-iso: Creating floppy disk...
virtualbox-iso: Copying files flatly from floppy_files
virtualbox-iso: Copying file: ./answer_files/10/Autounattend.xml
virtualbox-iso: Copying file: ./floppy/WindowsPowershell.lnk
virtualbox-iso: Copying file: ./floppy/PinTo10.exe
virtualbox-iso: Copying file: ./scripts/fixnetwork.ps1
virtualbox-iso: Copying file: ./scripts/disable-screensaver.ps1
virtualbox-iso: Copying file: ./scripts/disable-winrm.ps1
virtualbox-iso: Copying file: ./scripts/enable-winrm.ps1
virtualbox-iso: Copying file: ./scripts/microsoft-updates.bat
virtualbox-iso: Copying file: ./scripts/win-updates.ps1
virtualbox-iso: Done copying files from floppy_files
virtualbox-iso: Collecting paths from floppy_dirs
virtualbox-iso: Resulting paths from floppy_dirs : []
virtualbox-iso: Done copying paths from floppy_dirs
==> virtualbox-iso: Creating virtual machine...
==> virtualbox-iso: Creating hard drive...
==> virtualbox-iso: Attaching floppy disk...
==> virtualbox-iso: Creating forwarded port mapping for communicator (SSH, WinRM, etc) (host port 2734)
==> virtualbox-iso: Executing custom VBoxManage commands...
virtualbox-iso: Executing: modifyvm windows_10 --memory 2048
virtualbox-iso: Executing: modifyvm windows_10 --cpus 2
==> virtualbox-iso: Starting the virtual machine...
virtualbox-iso: The VM will be run headless, without a GUI. If you want to
virtualbox-iso: view the screen of the VM, connect via VRDP without a password to
==> virtualbox-iso: Waiting 6m0s for boot...
==> virtualbox-iso: Typing the boot command...
==> virtualbox-iso: Waiting for WinRM to become available...