You could use a macro that saves a copy in your favorite backup folder and then
marks the file readonly (the windows attribute).
Option Explicit
Sub testme01()
Dim myPath As String
Dim myFileName As String
myPath = "C:\backups"
If Right(myPath, 1) <> "\" Then
myPath = myPath & "\"
End If
With ThisWorkbook
'save the workbook
.Save
myFileName = myPath & .Name
On Error Resume Next 'in case it's not there
'vbNormal will allow the code to overwrite the file
SetAttr pathname:=myFileName, attributes:=vbNormal
On Error GoTo 0
.SaveCopyAs Filename:=myFileName
SetAttr pathname:=myFileName, attributes:=vbReadOnly
End With
End Sub
