I have, in my research collection, a couple of plaster casts of small medallion specimens from the Ashmolean Museum in Oxford from the time of Gallienus.
The first specimen, approximately 23mm in diameter, is from the joint reign of Gallienus with his father, Valerian. The obverse is CONCORDIA AVGVSTORVM, laureate and cuirassed bust of Gallienus to right, facing a laureate and draped bust of Valerian I. The reverse is LIBERALITAS AVGG I, two emperors seated left on a platform, behind them is the praetorian prefect and an attendant, in front Liberalitas holding tessera and a cornucopia, plus also a citizen on the stairs, MIR 329d. The issue dates to autumn AD 253 and commemorates a donativa paid on their entry into Rome.
The second specimen, oversize flan approximately 26mm across, dates to AD 264, during the sole reign of Gallienus (MIR 563a, Rome mint, 8th emission). The type is only known from specimens struck in bronze, although, it is a period when a range of base metal strikes from dies intended for the production of gold pieces and so the Oxford piece may be from the dies produced for a four aurei piece that is now lost.
The legend on the obverse is unusual in that it read GALLIENVM AVG P R, the accusative tense, roughly translated as the Roman people thank Gallienus. This is paired with OB CONSERVATIONEM SALVTIS, Salus walking right feeding a serpent in arms. It is from the period when Gallienus had turned his military campaign towards Postumus in the West and the early successes were providing security for the Roman state, a situation that would not last as Gallienus suffered a thigh wound in one encounter that precipitated a tactical withdrawal.
I do lament the passing of the times when institutions would either prepare casts for you, or even let you take your own. It is, I think, a reflection on the ease of digital photography but there is still something to be said for having a physical object.
