**4. Rapid physical models**

Three distinct advances in machining technology has paved the way for rapid physical models in the last 25 years or so. At first, emergence of **high-speed CNC** milling machines in various sizes allowed model makers to fully utilise its capabilities for model making for industrial design.

Second is the emergence of two-dimensional computer-controlled **laser cutters**, which operate on the same drafting principle of a graphic plotter. This allowed for quick machining of 2D shapes in both opaque and transparent materials. It has been

<sup>5</sup> https://www.cadcrowd.com/blog/top-file-formats-for-sharing-3d-and-2d-cad-designs/

**Figure 13.** *Concept irons from students.*

**Figure 14.** *3D printed spectacle frames (source: 3ders.org).*

said that the famous Silicon Valley in California, USA, has overplayed the contribution of laser cutters in the development of hi-tech products.

Third, and the most influential technology in the development of rapid model making is introduction of additive manufacturing, which is also known as **3D printing**. 3D printing is not one technology but many that has been developed by several companies/corporation based on the principle that a model can be built, layer by layer, using materials that are deposited or extruded and cured to solid state as the layers are added. Looking at the history of 3D printing the first technology to emerge around 1984 was **Stereolithography** followed by Selective Laser Sintering (**SLS**) in 1988 which was then followed by Fusion Deposition Modelling (**FDM**). Several companies manufacture 3D printers in what is now a competitive market which cater to institutions and professional companies/outfit that could purchase and maintain a high-end rapid model making equipment. Since 2010, table top 3D printers that are much lower in cost and easy to maintain have become popular allowing not only designers, but craftspeople and hobby enthusiasts to purchase them.
