The driving force to solve these problems comes from the early adopters whose present applications already possess an overwhelming balance in favor of additive fabrication. These individuals and companies are providing the foundation upon which further improvements will be based.

Geometric freedom.
Essentially all additive fabrication technologies provide the ability to fabricate with unbounded geometric freedom. It's their most important advantage over subtractive methods and main reason to exist. Geometric freedom comes with several limitations using today's technology, however. The speed of fabrication compared to standard manufacturing methods is much slower. By some estimates, existing mass production methods are 10 to 1,000 times faster [1]. The finishes and accuracy are also not on a par with conventional technology. Secondary operations are also required, such as support removal and hand-finishing. In a production situation, where multiple parts are fabricated, secondary operations can add up and become time-consuming. There are also part size limitations at present which are more restrictive than those of standard methods.

Materials.
Additive fabrication offers the potential to use multiple materials as well as to control the local geometric meso- and micro-structure of a part. This means that the functionality of a part can be optimized in ways that are impossible with previously existing manufacturing methods. Materials can be selected for their mechanical, thermal, optical or other properties, and then can be physically deposited in a manner that optimizes or changes those properties beyond the capability of the intrinsic material itself.

On the other hand, the reality today is that the key word here is "potential." It will be a long time before the choice of materials available to rapid manufacturing is even remotely comparable to those available to standard manufacturing technologies. There are just a few dozen RP/RM materials commercially available today, spread out over all classes of materials such as plastics, metals and ceramics. In contrast, plastic selection databases exist that list a mind-boggling 40,000+ active grades of plastic alone [2]. In addition, recycling complex materials may be difficult or impossible.

Elimination of tooling.
CAD directly drives all additive fabrication processes, making it theoretically possible to avoid the use of tooling altogether. In practice, it may often still not be possible to do that because of process and materials limitations of one kind or another, but complementary rapid tooling technology might offer a beneficial compromise. When feasible, however, the complete elimination of tooling results in enormous savings in time and money. It makes it possible to fabricate parts and products in small quantities, or using materials and design parameters that might not otherwise be conceivable.

Lowered costs.
The ability to fabricate products more economically arises from several links in the RM process chain: One of the largest savings, as mentioned, is doing away with the need for tooling. Additional savings arise from lowered or zero inventory requirements, and eventually can be expected to also arise from the ability to fabricate complete operational assemblies. The latter further lowers inventory costs and also does away with assembly labor. Of course, the economic potential described here requires substantial technological development to fully realize.

The establishment of distributed manufacturing is simplified once tooling and inventory requirements are done away with. Parts and products can be fabricated at the point of use and in the exact quantity required. For example, parts may be manufactured at the location of the final assembly line, or at a replacement part distribution site, or on a ship at sea or in outer space. It will only be necessary to inventory the requisite materials rather than many parts or sub-assemblies, or even the final product itself.

Mass customization.
Taking distributed manufacturing to its logical extreme, one of the major reasons that some pundits are excited by the possibilities of RM is that it holds promise to lead to an era of products designed directly by consumers. If it's possible to economically make as few as a single unit of an item, then it's hypothesized that there will develop a significant demand for products created by and for individual consumers. Such products might be expected to satisfy consumers' needs more precisely than mass-produced goods.

This scenario is predicated at least to some extent by extrapolating on the many examples of semi-custom designed products available in the marketplace today. Automobiles, personal computers and houses are all built with significant customer input. Cell phone covers, watch face designs and other fashion items over the last several years have also become products that offer consumers personalized choice. The trend can be expected to continue, especially for some items, and for certain consumer groups. However, these are all products that are either based on a limited, but nevertheless large mix and match menu, or for which functionality is not seriously impacted. The question remains, will we all be designing our own sneakers, automobiles, toys and toasters in the not too distant future? The answer is that that's not likely to happen.

Arguments Against Mass-customization...