Born in Urbino on March 19, 1717, Nini began his training as an engraver under his father. He studied sculpture at the Accademia Clementina. Around 1740 became the superintendent of a glassworks near Madrid, Spain. By 1758 he moved to Paris and worked as an engraver. In October 1772, Nini signed a contract to superintend the Jacques Donatien Le Ray's factories at Chaumont-sur-Loire, a glass and ceramics workshop. In addition to overseeing the factory, Nini could create whatever works of art he wanted.

Nini executed his medallions in terra cotta cast from moulds carved directly in wax. Nini added details to the terracotta casts before the casts were baked. As he used terracotta and not bronze, the wax molds held their images well and he could a produce a high number of medallions from a single mold. He did appoximately 100 different medallions, none of which have a reverse. A friend of Franklin, Nini created the most popular and most frequently repeated likenesses of Franklin. Nini died at Chaumont-sur-Loire on May 2, 1786.