A more distant target is dematerialization, making the products gradually smaller and lighter, and finally perhaps substituting some of them with non material services like e-mail and the virtual services of the personal computer. The upper part of the model on the right is often used as a starting point in ecological studies of manufacture, while its mirror image in the lower part is a popular model in economic research. Of course, both halves of the picture have to be taken into account in the practical management of manufacture. Here too the purpose of research is to minimize the waste generated during product manufacture, simplify the reuse of products and their components, and minimize energy and material consumption and other negative impacts of product use. Product designers have a great influence on the ecology of manufacture because they have much freedom in selecting the materials and components of products, including the use of reprocessed materials.
Clever design can also reduce the amount of materials needed in a product.
For instance, an inherently rigid three-dimensional shape for the product can allow using lower gauge metal sheet in its construction. Nevertheless, the stage of product assembly offers many new opportunities for reducing the use of materials, particularly toxic ones, and minimizing wastes. Immense amounts of metals and other raw materials are continually lost to productive use as a result of their dilution or minute concentrations in wastes. Metals can be found in rinse waters from metal finishers, stack emissions and pollution control sludge from coal fired power plants, and baghouse dusts from metal smelters among others. In a national analysis of metals concentrations in waste streams in the US, researchers have found that metal concentrations are frequently higher in waste stream compared with those in typical ore bodies.