Format-NewBootableUSB.ps1

function Format-NewBootableUSB() {
    [CmdletBinding(DefaultParameterSetName='Default')]
    Param(
        [Parameter(Position=0,Mandatory=$True,ParameterSetName='Default')]
        [Parameter(Position=0,Mandatory=$True,ParameterSetName='CopyOnly')]
        [String]$FirstPartitionSourceFolder,

        [Parameter(Position=1,ParameterSetName='Default')]
        [Parameter(Position=1,ParameterSetName='CopyOnly')]
        [String]$SecondPartitionSourceFolder,

        [Parameter(Position=2,ParameterSetName='Default')]
        [String]$FirstPartitionName,

        [Parameter(Position=3,ParameterSetName='Default')]
        [String]$SecondPartitionName,

        [Parameter(ParameterSetName='CopyOnly')]
        [Switch]$CopyOnly,

        [Parameter(Position=2,ParameterSetName='CopyOnly')]
        [String]$FirstPartitionDriveLetter,

        [Parameter(Position=3,ParameterSetName='CopyOnly')]
        [String]$SecondPartitionDriveLetter
    )
    $ErrorActionPreference='Stop'
    if (-not $PSBoundParameters.ContainsKey('CopyOnly')) {
        If (-not ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
            throw 'Format-NewBootableUSB must be run as Administrator'
        }
        $disks = Get-Disk | Where-Object {$_.Path.StartsWith('\\?\usbstor#disk')}
        if ($null -eq $disks -or $disks.Count -eq 0) {throw "Please insert a USB device first."}
        $disk = $disks | Sort-Object -Property "Number" | Out-GridView -Title 'Which disk do you want to format?' -PassThru
        if ($null -eq $disk) {
            $disk = Get-Disk -Number $(disks | Sort-Object -Property "Number" | ForEach-Object { Get-Partition -DiskNumber $_.Number 2>$null } | Out-GridView -Title 'Which drive do you want to format?' -PassThru).DiskNumber
            if ($null -eq $disk) {
                Return
            }
        }
        if ($PSVersionTable.PSVersion.Major -le 5) {
            # PowerShell Core appears to not require this to be loaded.
            try {[Void][System.Reflection.Assembly]::LoadWithPartialName('Microsoft.VisualBasic')} catch {throw}
        }
        if ([String]::IsNullOrWhiteSpace($FirstPartitionName)) {
            $FirstPartitionName = [Microsoft.VisualBasic.Interaction]::InputBox('Enter a name for the first partition (Windows boot media)','Partition 1','WinPE')
        }
        if ([String]::IsNullOrWhiteSpace($FirstPartitionName)) {Return}
        if ([String]::IsNullOrWhiteSpace($SecondPartitionName)) {
            $SecondPartitionName = [Microsoft.VisualBasic.Interaction]::InputBox('Enter a name for the second partition (images/scripts/etc)','Partition 2','Images')
        }
        if ([String]::IsNullOrWhiteSpace($SecondPartitionName)) {Return}
        $diskNum = $disk.Number

        $response=(New-Object -ComObject "WScript.Shell").PopUp("Proceeding to completely clean and format Disk $diskNum.`nDisk $diskNum contains the following partitions:`n$(Get-Partition -DiskNumber $diskNum|Out-String)`n`nAre you sure you wish to proceed?",$null,"Formatting Disk #$diskNum",49)

        if ($response -ne 1) {
            # User did not click OK
            Return
        }

        Clear-Disk -Number $diskNum -RemoveData -RemoveOEM -Confirm
        Reset-PhysicalDisk -UniqueID $Disk.UniqueID
        # $disk = Initialize-Disk -Number $DiskNum -PartitionStyle MBR -PassThru

        $FirstPartitionDriveLetter = Get-FirstAvailableDriveLetter
        $FirstPartition = New-Partition -DiskNumber $diskNum -Size 2GB -IsActive:$True
        $FirstPartition | Format-Volume -FileSystem FAT32 -NewFileSystemLabel $FirstPartitionName
        $FirstPartition | Set-Partition -NewDriveLetter $FirstPartitionDriveLetter
        Bootsect /Nt60 "$($FirstPartitionDriveLetter):"
        $FirstPartition | Set-Partition -IsHidden $True -ErrorAction Continue # This was failing for some reason.

        $SecondPartitionDriveLetter = Get-FirstAvailableDriveLetter
        $SecondPartition = New-Partition -DiskNumber $diskNum -UseMaximumSize
        $SecondPartition | Format-Volume -FileSystem NTFS -NewFileSystemLabel $SecondPartitionName
        $SecondPartition | Set-Partition -NewDriveLetter $SecondPartitionDriveLetter
    }
    if ($null -ne $FirstPartitionDriveLetter -and $PSBoundParameters.ContainsKey('FirstPartitionSourceFolder') -and ([System.IO.DirectoryInfo]$FirstPartitionSourceFolder).Exists) {
        cmd /c "robocopy `"$($FirstPartitionSourceFolder)`" $($FirstPartitionDriveLetter):\ /E /ZB /J /FFT /DCOPY:DAT /NJH /R:1 /W:1 /XD `"$($FirstPartitionDriveLetter):\System Volume Information`" `"$($FirstPartitionSourceFolder)\System Volume Information`""
    }
    if ($null -ne $SecondPartitionDriveLetter -and $PSBoundParameters.ContainsKey('SecondPartitionSourceFolder') -and ([System.IO.DirectoryInfo]$SecondPartitionSourceFolder).Exists) {
        cmd /c "robocopy `"$($SecondPartitionSourceFolder)`" $($SecondPartitionDriveLetter):\ /E /ZB /J /DCOPY:DAT /NJH /R:1 /W:1 /XD `"$($SecondPartitionDriveLetter):\System Volume Information`" `"$($SecondPartitionSourceFolder)\System Volume Information`""
        if ($? -eq $False) {Return}
    }
}

function Get-FirstAvailableDriveLetter() {
	for($j=67; Get-PSDrive([char]$j) -ErrorAction Ignore){
		$j++
	}
	[char]$j
}