The traditional three-point pointing machine used to reproduce a sculpture at 1:1 scale by transferring measured surface coordinates from a model to stone.
Macchinetta is the traditional pointing machine used in marble copying. It may be made of wood or metal and is fixed to three prominent reference points—the capipunti. An articulated arm ending in a fourth point can then be adjusted in multiple directions to locate additional surface coordinates.
Le voci del marmo specifically notes its use for reproduction at 1:1 scale.
Etymology
Italian diminutive of macchina, “machine”; literally “little machine.”
Sculptor Notes
The macchinetta does not carve the sculpture; it tells the carver where the intended surface exists in space. The craft lies in approaching those measured points without damaging the final surface.
References
https://levocidelmarmo.sns.it/scheda_oggetti_relazione.php?denom=macchinetta&id=47