The Roman army was a vast military machine that demanded huge amounts of material and complex supply mechanisms. A 14kg hoard of mail armour from near the Roman legionary fortress of Bonn, Germany, offers insight into the organisation of recycling and repair on Rome's northern frontier. Computed tomography reveals there are at least four garments and suggests a likely date. The authors explore the hoard's context and motivations for its deposition and non-retrieval, arguing it formed a collection of ‘donor’ mail for repairing other mail garments. Its discovery in a settlement outside the military fortress indicates the involvement of local craftworkers. The settlement was abandoned in the mid-third century AD.