Excel VBA macro to generate a list of possible combinations

You can use the following to cross join two different ranges. It will handle ranges of any size and write the crossjoined combinations to a target sheet that you specify.

In the example below, I have defined two named ranges: newValues and fixedValues. Both of these ranges are on Sheet1. I then loop through the ranges and write all combinations to Sheet2.

Sub CrossJoinMyRanges()
    Dim ws As Worksheet
    Dim newValues As Range
    Dim cell As Range

    Set ws = ThisWorkbook.Sheets("Sheet1")
    Set newValues = ws.Range("newValues")

    ' loop through the new values
    For Each cell In newValues
        Call ReplaceMe(cell.Value, ws)
    Next cell
End Sub

Sub ReplaceMe(replacement As String, ws As Worksheet)
    Dim fixedValues As Range
    Dim cell As Range

    Set fixedValues = ws.Range("fixedValues")

    ' outer loop through fixedValues
    For Each cell In fixedValues
        Call PrintReplacedValues(cell.Row, replacement)
    Next cell
End Sub

Sub PrintReplacedValues(rowNumber As Long, replacement As String)
    Dim wb As Workbook
    Dim src As Worksheet
    Dim tgt As Worksheet
    Dim fixedValues As Range
    Dim cell As Range
    Dim printMe As String
    Dim x As Long, y As Long

    Set wb = ThisWorkbook
    Set src = wb.Sheets("Sheet1")
    Set tgt = wb.Sheets("Sheet2")
    Set fixedValues = src.Range("fixedValues")
    y = 1
    x = tgt.Range("A" & tgt.Rows.Count).End(xlUp).Row + 1

    ' inner loop through fixed values
    For Each cell In fixedValues
        ' replace the fixed value with the replacement
        ' if the loops intersect
        If cell.Row = rowNumber Then
            printMe = replacement
        Else
        ' otherwise keep the fixed value
            printMe = cell
        End If
        ' write to the target sheet
        tgt.Cells(x, y).Value = printMe
        y = y + 1
    Next cell
End Sub

There are a few similar questions with alternative solutions that you can also look into if my approach isn't what you were after:

Excel vba to create every possible combination of a Range

How can i obtain cartesian product like columns in excel?