An apparatus and method for fabricating a three dimensional model from a
composite model formed or a plurality of successive layers of model
material and sacrificial mold material. Each successive layer is
constructed by depositing, drop-by-drop, at least one line of sacrifical
mold material delineating at least one boundary of the model material
within the layer and thereafter depositing the model material onto all
delineated regions of the layer by spray deposition. Each successive
layer is completed by a planing process which removes the undesired
thickness of both the sacrificial and the model materials. Following
completion of the composite model, the sacrificial mold material is
removable from the composite model, by a process effecting only the
sacrificial mold material, to produce the three dimensional model. A
device, for depositing the model material at the rate faster than the
rate that the mold material is deposited, is also described.