// Tested with Windows Server 2016. //

This lists the quick steps to create a bootable Windows installer on USB disk without using extra tools.

Follow Thomas Maurer - Create a USB Stick for Windows Server 2016 Installation.

In short:

1. Start an elevated command prompt:
2. Start diskpart and use it to:
   1. List the disks.
   2. Select the USB disk.
      1. // In this example the USB disk is on disk 1, please check your output of list disk to determine which number the USB disk is on before proceding with select disk. //
   3. Clean the USB disk.
   4. Create one primary partition.
   5. Format that partition with FAT32.
   6. Mark the partition active (bootable).
   7. Assign the USB disk a drive letter (K: in this example).
   8. // The below commands assume the USB disk is disk 1, with the only other disk being 0 the OS disk. //

      diskpart
      list disk
      select disk 1
      clean
      create partition primary
      format fs=FAT32 quick
      active
      assign letter=k
      exit

3. Mount the Windows server 2016 DVD (i.e. double-click the ISO in explorer to have it mounted on for example D:\ as in this example).
4. Copy the contents of the ISO to the USB disk.
   1. Skip install.wim as we need to split it to overcome the FAT32 max 4 GB per file limit.
   2. Skip autorun.inf to prevent an on-access anti-virus scanner from interfering.

      robocopy d:\ k:\ /E /XF install.wim /XF autorun.inf

   3. Split the install.wim in max 4 GB pieces and write those pieces to the USB disk:

      dism /Split-Image /ImageFile:D:\sources\install.wim /SWMFile:k:\sources\install.swm /FileSize:4096