Patent ID: 8580869

Claim:
A shaped, seamless model free of bond lines made by a method comprising the sequential steps of: providing a substructure having an exposed outer surface, the substructure forming part of the seamless model; providing separate tanks filled with a resin comprising an organic polyisocyanate component and a hardener system comprising (1) a polyol component comprising (i) greater than 60% by weight of a high molecular weight polyol and (ii) less than 40% by weight of a low molecular weight polyol based on the total weight of the combined polyol component; (2) a chemical thixotropic agent; (3) microballoons; and (4) a surfactant; delivering the resin and hardener system from the tanks to a mix block where the resin, hardener system and an inert gas are mixed under high shear to produce a modeling paste of uniform density; applying the modeling paste to the outer surface of the substructure in the form of a continuous layer; curing the continuous layer of applied modeling paste in situ on the substructure at room temperature; and machining said cured layer of modeling paste in situ on the substructure to the desired contour to form the model and wherein the model has a bulk density of between 0.3 g/cm 3 to 0.9 g/cm 3 .