Creating combinations of text from a table

sampie13 

Here is a macro solution:

Sub CreateCombinations()
    Const c = "K" ' Output column
    Dim r As Long
    Dim r1 As Long, r2 As Long, r3 As Long, r4 As Long
    Dim m1 As Long, m2 As Long, m3 As Long, m4 As Long
    Application.ScreenUpdating = False
    m1 = Range("C1").End(xlDown).Row
    m2 = Range("D1").End(xlDown).Row
    m3 = Range("E1").End(xlDown).Row
    m4 = Range("F1").End(xlDown).Row
    r = 1
    For r1 = 2 To m1
        For r2 = 2 To m2
            For r3 = 2 To m3
                For r4 = 2 To m4
                    r = r + 1
                    Range(c & r).Value = Range("C" & r1).Value & "_" & Range("D" & r2).Value & _
                        "_" & Range("E" & r3).Value & "_" & Range("F" & r4).Value
                Next r4
            Next r3
        Next r2
    Next r1
    Application.ScreenUpdating = True
End Sub