Most of the existing rapid prototyping processes are still quite expensive and many of them generate substances such as smoke, dust, hazardous chemicals, etc., which are harmful to human health and the environment. Dr. Ming Leu of the University of Missouri-Rolla, Virtual & Rapid Prototyping Lab. is developing a rapid prototyping process that uses cheap and clean materials and can achieve good layer binding strength, fine build resolution, and fast build speed. They have invented such a process, called Rapid Freeze Prototyping (RFP), that can make three-dimensional ice parts of arbitrary geometry layer-by-layer by freezing of water droplets.