184 Glossary There are a number of key words relating to the practice of architectural modelmaking that are typically understood by everyone but may be interpreted differently, giving rise to ambiguity if not misunderstanding. In the interest of clarity, it is valuable to provide a definition of the more significant words and phrases used in this book. Perhaps most importantly, it is worth starting with a term that can result in much confusion depending on how it is used: model. Model There are multiple entries under the dictionary definition of a model although "a representation, generally in miniature, to show the construction or appearance of something" may seem the most appropriate in this context. However, even this definition is rather limiting as it does not emphasize the dynamic role the model has. For the purpose of this book it is important to consider a model as both the medium and mechanism through which design ideas are generated and represented. CAD Computer-Aided Design (or Drafting) software is used by architects and students to develop and communicate their development. In architecture, the experimental nature of the discipline often requires the need for prototyping to enable the designer to explore, test, and evaluate potential solutions. Rapid prototyping is an automatic process of making physical models using additive manufacturing technology by taking the data from CAD files and converting it into successive layers of liquid, powder, or sheet material, to build up a model from a series of cross sections. These layers are then bonded together to produce the final form. The key advantage of this technique is its ability to create almost any form or geometric feature. Representation carries several different meanings but in this context it is used to describe the communicative aspects of a model, that is to say it is a mode of expression for design ideas rather than a generator of them. Scale is described as a ratio in relation to reality and enables architects and students to accurately describe design ideas in drawings and models. The specific scale used may be metric or imperial but care should always be taken when converting from one scale to another.