Frank Willer from the department for metal restoration at the Landesmuseum Bonn inspects a Roman steelyard under a Keyence microscope (photograph: Jochen Büttner). The finest traces of the original workmanship are visible under the microscope, which can give information about the process of production. It can thus for instance be determined whether the eyelets on a balance—which must be placed with the utmost precision—were originally included in the casting process or whether they were subsequently drilled and scratched out with an awl.