A multi-tip extrusion method and apparatus for building a three-dimensional object
deposits modeling materials from distinct supply sources, each in a layerwise predetermined
pattern, from dispensers having co-planar dispensing tips. The tip spacing is controlled
so that a road of material extruded by a leading one of the tips will cool and
shrink from the plane of the tips before a trailing one of the tips passes over
the road. In this manner, smearing of the road by a trailing one of the tips is avoided.