Sub TryScramble()
    MsgBox ScrambleWords("Utter", "Access")
End Sub

Function ScrambleWords(String1 As String, String2 As String) As String
    Dim w1() As Byte, w2() As Byte
    Dim i As Long
    w1 = UCase(String1)
    w2 = UCase(String2)
    On Error Resume Next
    For i = LBound(w1) To UBound(w1)
        If w1(i) > 0 Then
            ScrambleWords = ScrambleWords & Chr$(w1(i))
            ScrambleWords = ScrambleWords & Chr$(w2(i))
        End If
    Next i
    If UBound(w2) > UBound(w1) Then _
        ScrambleWords = ScrambleWords & Right$(w2, Len(String2) - Len(String1))
End Function

Sub TryScramble2()
    MsgBox ScrambleWords2("Utter", "Access", "Whatever", 123456)
End Sub
Function ScrambleWords2(ParamArray Words() As Variant) As String
    Dim w() As Byte, y() As Long
    Dim i As Long, j As Long, MaxLen As Long
    '
    'find max length and redim the array
    For i = 0 To UBound(Words)
        If MaxLen < Len(Words(i)) Then MaxLen = Len(Words(i))
    Next i
    ReDim y(0 To UBound(Words), 0 To 2 * MaxLen - 1)
    '
    'fill the array with bytes
    For i = LBound(y, 1) To UBound(y, 1)
        w() = CStr(Words(i))
        For j = LBound(w) To UBound(w)
            y(i, j) = w(j)
        Next j
    Next i
    '
    'concatenate the string from the bytes
    For j = LBound(y, 2) To UBound(y, 2)
        For i = LBound(y, 1) To UBound(y, 1)
        If CBool(y(i, j)) Then _
            ScrambleWords2 = ScrambleWords2 & UCase(Chr$(y(i, j)))
        Next i
    Next j
End Function

Function ScrambleWords3(ParamArray Words() As Variant) As String
    Dim w() As Byte, y() As String
    Dim i As Long, j As Long, MaxLen As Long
    '
    'find max length and redim the array
    For i = 0 To UBound(Words)
        If MaxLen < Len(Words(i)) Then MaxLen = Len(Words(i))
    Next i
    ReDim y(0 To MaxLen * (UBound(Words) + 1) - 1)
    '
    'fill the array scrambled characters and join
    For i = LBound(Words) To UBound(Words)
        w() = StrConv(CStr(Words(i)), vbFromUnicode)
        For j = LBound(w) To UBound(w)
            y(j * UBound(Words) + i) = Chr$(w(j))
        Next j
    Next i
    ScrambleWords3 = Join(y, vbNullString)
End Function