The excavation of the copper cementation workshop “Le Clos-Paul” in Charleville-Mézières (Ardennes, France), executed by the Cellule d’archéologie du Conseil départemental des Ardennes, led to the finding of fragments of coinage moulds. Dating from the middle of the 3rd century AD, they are the only evidence of an opportunistic production of counterfeits without any direct link to the metallurgical activity of the site. The study of the moulds led to a series of experimentations aimed at understanding the counterfeiting activity in its entirety, from the preparation of the loam intended for moulds to the casting of coins.