computer-side of the interaction is faked by an offsite or hidden human. This prototyping technique is particularly useful for demonstrating functionality that is difficult or lengthy to engineer, such as applications like voice user interface. role prototype: this prototype may not be engineered or look and feel like a finished product, but the purpose of this type of prototype is to investigate and evaluation a user need, or what the prototype could do for the user. They can present features and functionality that the user might benefit from, to demonstrate what role an artifact like the prototype might fulfill for the user. A famous example of this kind of prototype would be the block of wood carried by Jeff Hawkins, when developing the Palm Pilot. paper prototype: this prototype may use cut paper, cardboard, or other inexpensive materials to demonstrate an interface. The purpose of this prototype is to test with users, without having to use a digital tool or develop a program to test functionality. Recently, paper prototyping has fallen out of favor within certain design circles, particularly because the low-fidelity nature of this method and the lack of effectiveness when testing with users. Scale modeling In the field of scale modeling (which includes model railroading, vehicle modeling, airplane modeling, military modeling, etc.), a prototype is the real-world basis or source for a scale model—such as the real EMD GP38-2 locomotive—which is the prototype of Athearn's (among other manufacturers) locomotive model. Technically, any non-living object can serve as a prototype for a model, including structures, equipment, and appliances, and so on, but generally prototypes have come to mean full-size real-world vehicles including automobiles (the prototype 1957 Chevy has spawned many models), military equipment (such as M4 Shermans, a favorite among US Military modelers), railroad equipment, motor trucks, motorcycles, and space-ships (real-world such as Apollo/Saturn Vs, or the ISS). As of 2014, basic rapid prototype machines (such as 3D printers) cost about $2,000, but larger and more precise machines can cost as much as $500,000. Architecture In architecture, prototyping refers to either architectural model making (as form of scale modelling) or as part of aesthetic or material experimentation, such as the Forty Wall House open source material prototyping centre in Australia. Architects prototype to test ideas structurally, aesthetically and technically. Whether the prototype works or not is not the primary focus: architectural prototyping is the revelatory process through which the