Get-ChildItem $SourceFolder -Include $ExtArray -Recurse | forEach {
## Remove the original  root folder

  $split = $_.Fullname  -split '\'

  $DestFile =  $split[1..($split.Length - 1)] -join ''

  ## Build the new  destination file path

  $DestFile =  "C:DestinationFolder$DestFile"

  ## Copy-Item won't  create the folder structure so we have to

  ## create a blank file  and then overwrite it

  $null = New-Item -Path  $DestFile -Type File -Force

  Copy-Item -Path  $_.FullName -Destination $DestFile -Force

}