Basically there are six separate and very different techniques that are used in rapid prototyping depending on what exactly the result is that you are wanting for your prototype. With every technique is new machinery needed as well. One of the most common techniques is called stereolithography. This was a big word for a not so big process. Usually liquid resin is used because it solidifies whenever it is placed under an ultraviolet light or a black light. Since this is the most common this is the first option offered to many mainly because most RP sites also have stereolithography machinery as well. There is one major flaw in this system, the ending result can be very brittle and fragile no matter how tenderly someone handles it. Although it is a cheaper method depending on how much the prototype will be handled is one main point to consider before making a final decision on this technique.