Depending on the technical and aesthetic requirements specific to the building, metalworkers must be able to customise their work and work with unusual metal structures. They dismantle almost all the windows in the façade of the Chapel, glazing beads (metal panels/framework used to hold the glass), crosses, and all metal structures until everything has been stripped away. They replace all glass parts with aluminium to provide protection the windows are sanded clean.
After a meticulous examination of the state of the windows, the metalworkers have to duplicate the well-preserved parts in order to construct other identical parts to replace those that are too damaged. After the stained glass has been reinstalled by the master glaziers, the metalworkers reassemble the whole structure and commence the long task of drilling and boring during which tens of thousands of screws are positioned. One of the difficulties of this part of the works is that everything is done on-site and not in the workshop, where all the necessary machines are normally to hand. The metalworkers must also respect deadlines as closely as possible, as their progress enables other players, such as painters and gilders, to intervene after them. Taking part in a restoration of this scale on an historic monument is a rare and joyful opportunity for these craftspeople. Certain stages of the restoration necessitated the intervention of 8 metalworkers.