You could put this macro in the ThisWorkbook module, but it's easily
bypassed (by holding down the shift key on startup). And it doesn't
prevent the user from copying a sheet and pasting it into another
workbook - generally, you should assume that if a user can open your
workbook, that they have free access to your data and can print,
copy , save, etc. at will.
Private Sub Workbook_BeforePrint(Cancel As Boolean)
Cancel = True
End Sub
