The machine is mounted on a richly decorated wooden frame. A handle moves a wheel that rotates a small vertical boxwood plate by means of a pulley. The lenses to be ground were attached to the plate. The wheel axle also moves a series of toothed gears that simultaneously actuate a disk with different gear ratios (on which the lenses are mounted) and a tool holder that could be lowered. Some parts are missing. The instrument's construction and decoration suggest that it was more a demonstration apparatus than an efficient machine-tool. However, it may have been designed for cutting and cleaning semi-precious stones. The 1776 inventory of the Museo di Fisica e Storia Naturale listed Andrea Frati as the inventor.