The process, known as rapid freeze prototyping, makes a part, e.g., an ice structure, by depositing water. The deposition needs to be controlled so water solidifies only when it reaches a substrate. For the solidification to take place, the substrate needs to be kept at a sub-zero temperature. When the structure grows, it starts to melt because the substrate, though maintained at liquid nitrogen temperature (−140 °C), will not be able to cool it. This requires the whole setup of a nozzle and the substrate to be kept inside a cold chamber (−20 °C) to prevent the structure from melting. Keeping the setup inside affects the water present either within the nozzle or in transit to the substrate, causing the water to start solidifying. Therefore, the nozzle is kept near the substrate to facilitate the reaching of water to the substrate before the water starts to lose its form due to solidification. Besides, the water is ejected from the nozzle using more than a critical pressure, so the flow of water is not obstructed by icing on the nozzle. The flow breaks the icing if obstructed.