Creates Random strings like passwords

Get-RandomString.ps1

function Get-RandomString {
  param(
    [Parameter()][ValidateRange(8, 4000)]
    [int]$MaxLength = 16,
    [Parameter()][ValidateRange(1,1000)]
    [int]$MinCountLowerCaseLetters=1,
    [Parameter()][ValidateRange(1,1000)]
    [int]$MinCountUpperCaseLetters=1,
    [Parameter()][ValidateRange(1,1000)]
    [int]$MinCountDigits=1,
    [Parameter()][ValidateRange(1,1000)]
    [int]$MinCountSpecialLetters=1
  )
  begin {
    $lowerCaseLetters = [char[]]@('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'w', 'x', 'y', 'z');
    $upperCaseLetters = [char[]]@('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'W', 'X', 'Y', 'Z');
    $digits = [char[]]@('1','2','3','4','5','6','7','8','9','0');
    $specialReadableAsciiCharacters = [char[]]@('!', '"', "'", '#', '$', '%', '&', '*', '+', ',', '.', '/', ':', ';', '=', '?', '@', '{', '}', '[', ']');
  }
  process {
    $requiredLength = $MinCountLowerCaseLetters + $MinCountUpperCaseLetters + $MinCountDigits + $MinCountSpecialLetters;
    if($MaxLength -lt $requiredLength) {
      throw "The maximum length of the password must be at least satisfy the required occurrences of the character groups.";
    } 
    $result = New-Object -TypeName char[] -ArgumentList $MaxLength;
    $randomIndizes = 1..$MaxLength | ForEach-Object { [pscustomobject]@{ Idx=$_-1;O=(Get-Random -Maximum $MaxLength) } } | Sort-Object -Property "O" | Select-Object -ExpandProperty "Idx";
    $requiredSet = @(1..$MinCountLowerCaseLetters | ForEach-Object { $lowerCaseLetters[(Get-Random -Maximum $lowerCaseLetters.Length)].ToString() });
    $requiredSet += @(1..$MinCountUpperCaseLetters | ForEach-Object { $upperCaseLetters[(Get-Random -Maximum $upperCaseLetters.Length)].ToString() });
    $requiredSet += @(1..$MinCountDigits | ForEach-Object { $digits[(Get-Random -Maximum $digits.Count)].ToString() });
    $requiredSet += @(1..$MinCountSpecialLetters | ForEach-Object { $specialReadableAsciiCharacters[(Get-Random -Maximum $specialReadableAsciiCharacters.Length)].ToString() });
    for($i = 0; $i -lt $MaxLength; $i++) {
      if($i -lt $requiredLength) {
        $result[$randomIndizes[$i]] = $requiredSet[$i];
        continue;
      }
      # the max length is greater than required minimum
      # so randomly select a character class and fill in the rest
      switch((Get-Random -Maximum 4)) {
        0 { $result[$randomIndizes[$i]] = $lowerCaseLetters[(Get-Random -Maximum $lowerCaseLetters.Length)] }
        1 { $result[$randomIndizes[$i]] = $upperCaseLetters[(Get-Random -Maximum $upperCaseLetters.Length)] }
        2 { $result[$randomIndizes[$i]] = $digits[(Get-Random -Maximum $digits.Count)] }
        3 { $result[$randomIndizes[$i]] = $specialReadableAsciiCharacters[(Get-Random -Maximum $specialReadableAsciiCharacters.Length)] }
      }
    }
    $(-join $result) | Write-Output;
  }
}