Andrei Herasimchuk posted this to the IxDA mailing list, as part of a (reasonably interesting, given the usual turgdity of the list) discussion. The quotation itself was just too good not to lift.

Too much emphasis cannot be placed on the importance of three- dimensional models. We come to this step after we have analyzed and evaluated hundreds of designs and blueprints, trying to bring some quality to the product that will make it easier to use without increasing the cost, more pleasant to look at without any drastic changes in the factory routine. When our ideas have been formulated, we design in clay, then plaster, finally in a material that will simulate the material to be used in manufacturing the actual product. Wherever possible, such models are done in full size. In developing the exterior of a train or a ship, accurate scale models must suffice.

The cost of a model is more than compensated for by future savings. It not only presents an accurate picture of the product for the executives, but it also gives the toolmakers and production men an opportunity to criticize and to present manufacturing problems. Models of some products can be made for a few hundred dollars. Full- scale models of ship or train interiors can cost many thousands of dollars. A mock-up of a modern passenger airplane cabin may cost $150,000 but it will be worth it, for it permits engineers and designers to develop techniques of installation that would not be otherwise possible. Furthermore, sales executives can bring potential customers into a faithful, full scale fuselage to see what it offers, long before production begins. It is far more effective to sit in a chair that judge its comfort by a picture of it.

Henry Dreyfuss, Designing for People, 61-62.

This doesn’t just apply to ships and trains, does it? We’re back to sculpting versus painting again.