## install homebrew first if not available
brew install wimlib

## list disks to find flashdrive disk number
diskutil list

## confirm flashdrive disk number and match to commands before proceeding
diskutil eraseDisk MS-DOS "W10" MBRFormat /dev/disk2

## download Windows 10 iso - https://www.microsoft.com/en-us/software-download/windows10ISO

## mount downloaded Windows 10 iso
hdiutil mount ~/Downloads/Win10_2004_English_x64.iso

## confirm volume is mounted and flash volume available
ls -lah /Volumes/CCCOMA_X64FRE_EN-US_DV9
ls -lah /Volumes/WIN10

## rsync files from mounted iso volume to flash volume - excludes over 4GB install.wim which must be split on Fat32 FS
rsync -vha --exclude=sources/install.wim /Volumes/CCCOMA_X64FRE_EN-US_DV9/ /Volumes/WIN10

## split >4GB install.wim into 1GB chunks and write to flash volume
wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WIN10/sources/install.swm 1024

## unmount flash volume and mounted iso volume
diskutil list
diskutil unmount /dev/disk2
diskutil unmount /dev/disk3

## install media complete!