As well known, in the reconstruction of the 3D models through optical systems, the errors are due to the single-view acquisition error and to the 3D modeling procedure. The latter can be ascribed to the various phases of the 3D modeling pipeline: pairwise registration, global registration, surface integration. This work examines the acquisition error as well as the errors due to an automatic procedure recently proposed for the 3D modeling of dental plaster casts. This contribution derives a simple error propagation model, rather useful for practical simulation purposes. From a general viewpoint, this contribution proposes a useful simulation of error propagation in 3D modeling, it shows the quality of an automatic 3D modeling procedure recently proposed and it shows the accuracy of 3D modeling dental plaster casts by current commercial range cameras and the considered automatic method.