Car manufacturers have been using small scale and full-scale clay models since the 1930s and it won't change any time soon. Here's the reason.

To make the full-size model, modelers start with a framework of the vehicle, typically made of foam. Over that, they smooth thousands of pounds of clay over one half of the car.

To make the full-size model, modelers start with a framework of the vehicle, typically made of foam. Over that, they smooth thousands of pounds of clay over one half of the car.

Despite advances in industrial-design software, executives at companies such as Ford, Chrysler and Toyota still want to see full-size physical models before committing to production.