I’ve had great success invoking the VirtualBox API directly – so no need to invoke an EXE file at all.

Try running:
PS>$vBox = New-Object -ComObject VirtualBox.VirtualBox
PS>$vBox | Get-Member
Then you’ll see the functions and methods of the API.

It’s worth downloading the API documentation from Oracle; they mention a lot of things here (though it’s not as well documented as I’d hoped for; I’d like more code examples….)

An example of how to do this: I wrote the following code to be able to quickly create a differencing disk based on any of my templates.
The

param ([string]$TemplatePath, [string]$DiffFormat = “vdi”, [string]$DiffPath)

#Set defaults so you don’t have to type the full path each time. If no drive letter is given, just append the input to the default paths.
$RootFolder = “c:\VMs”
$TemplateFolder = “c:\VMs\_Templates”

$MediumFixed = 65536
$MediumDiff = 131072

$vBox = New-Object -ComObject VirtualBox.VirtualBox
If ($? -eq $False) {
Write-Host “Connection to VBox COM object failed.”
Return
}
If ($TemplatePath -eq $null) {
Write-Host “Error. Missing parameter TemplatePath parameter.”
Return
}
If ($DiffPath -eq $null) {
Write-Host “Error. Missing DiffPath parameter.”
Return
}

$TemplateFilePath = “$TemplatePath”
If ($TemplatePath.Length -gt 3) {
If ($TemplatePath.Substring(1,2) -ne “:\”) {
$TemplateFilePath = “$TemplateFolder\$TemplatePath”
}
}

$DiffFilePath = “$DiffPath”
If ($DiffPath.Length -gt 3) {
If ($DiffPath.Substring(1,2) -ne “:\”) {
$DiffFilePath = “$RootFolder\$DiffPath”
}
}

$DiffHD = $vBox.CreateHardDisk($DiffFormat, $DiffFilePath)
If ($? -ne $True) {
Write-Error “Error trying to prepare the differencing hard disk.”
Return
}
$HDDDevType = $diffHD.DeviceType

$TemplateHD = $vBox.FindMedium($TemplateFilePath, $HDDDevType)
If ($? -ne $True) {
Write-Error “Error finding the template, or the template is not a proper hard disk file.”
Return
}

$CreateResult = $TemplateHD.CreateDiffStorage($DiffHD, $MediumDiff)
If ($? -ne $True -or $CreateResult.Resultcode -ne $Null) {
$ErrorMessage = $CreateResult.Resultcode
If ($ErrorMessage = -2135228412) { $ErrorMessage = “0x80BB0004 VBOX_E_FILE_ERROR” }
Write-Error “Error creating the differencing hard disk.
$ErrorMessage”
Return
}

A powerful share, I simply given this onto a colleague who was doing somewhat analysis on this. And …

(I’m going to need a to-do list just for PowerShell).

psedit myfile.ps1

Finally, since you aren’t processing any pipelined objects, you don’t really need the Begin and End script blocks. But overall a good construct.

[string]$base

Since you aren’t pipelining anything into the function the Begin/Process/End scriptblocks are irrelevant. I think you can just enter your code.

Take a look at Join-Path for constructing paths. I think it is a little easier to use and makes you less prone to concatenation errors.

What happens if the CreateVM expression fails? Or any of the other Invoke-Expression commands?

Since you are using cmdletbinding, why not add some Write-Verbose lines so the user can track what is happening or troubleshoot? All of your comments could easily become Write-Verbose lines. I also use Write-Verbose to show values of variables and parameters.

Finally, when you are ready to really go to the next level, you can add SupportsShouldProcess to the function (-WhatIf). But that’s the cherry on top of the icing on the cake.

Keep up the good work.