Dim tbo As New TextBox With _
           {.Multiline = True, .Parent = Me, _
            .Font = New Font("Courier New", 10), _
            .Top = 300, .Height = 100, .Width = 400}

Dim rndm As New Random(123)
 
Private Function GetU8() As Byte
   If rndm.Next(1, 5) = 4 Then Return CByte(Asc(" "))
   Return CByte(rndm.Next(Asc("A"), Asc("Z") + 1))
End Function

tbo.Text = ""
For i As Integer = 1 To 32
    'Zeichenfolge aufbauen
    Dim stb As New System.Text.StringBuilder(44)
    For j As Integer = 0 To 43
        stb.Append(Chr(GetU8))
    Next j
 
    'Index "formatieren"
    Dim num As String = ""
    If i <= 9 Then num = " "
    num &= CStr(i)
 
    'Zusammenfügen zu einem String und als Zeile anhängen  
    tbo.AppendText(num & "  " & stb.ToString.Trim() & vbCrLf)
Next i