Public Class exportWMF
    <CommandMethod("exportWMF")> _
    Public Sub exportWMF()
        On Error Resume Next
        Dim acadDoc As AcadDocument = Autodesk.AutoCAD.ApplicationServices.Application.AcadApplication.ActiveDocument
        Dim acadSSet As AcadSelectionSet = acadDoc.SelectionSets.Add("exportWmf")
        acadSSet.SelectOnScreen()
        acadDoc.Export("C:\exportWmf", "wmf", acadSSet)
        acadSSet.Delete()
    End Sub
End Class