Create an unbound combo box on a form select value list and add the following "Odd";"Even" as record source
="Odd" default value
add a command button with the following code
Sub Command5_Click()
On Error GoTo Err_Command5_Click
If Me!PrintPages = "Even" Then
MsgBox "Odd Pages will be Blank!"
Else
MsgBox "Even Pages will be Blank!"
End If
Dim stDocName As String
stDocName = "RptYourReportName"
DoCmd.OpenReport stDocName, acPreview
Me.Visible = Not Me.Visible
Exit_Command5_Click:
Exit Sub
Err_Command5_Click:
MsgBox Err.Description
Resume Exit_Command5_Click
End Sub