Abstract: Disclosed is a method and apparatus for making a prototype injection molded part. An extruder of the type used for fused deposition modeling injects production thermoplastic material into a heated nonconductive plastic mold tool slowly at low pressure in an isothermic process. The mold tool may be built from a CAD drawing by fused deposition modeling or another rapid prototyping technique. Using the present invention, an injection molded prototype part can be made from a digital representation of the part within 24 hours by an engineer in an office environment.

Abstract: 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.

Abstract: Disclosed is a multi-tip extrusion apparatus and design methodology whereby a single extrusion head having approximately co-planar, fixed-position dispensing tips is used in a three-dimensional modeling machine to deposit multiple types of materials from distinct material supply sources. The tips are spaced apart a distance great enough so that a road of material extruded by a leading one of the tips will cool and shrink from the plane of the tips so that it is not smeared by contact with a trailing one of the tips.