Nanotechnology offers the ability to build large numbers of products that are incredibly powerful by today's standards. This possibility creates both opportunity and risk. The problem of minimizing the risk is not simple; excessive restriction creates black markets, which in this context implies unrestricted nanofabrication. Selecting the proper level of restriction is likely to pose a difficult challenge.

A system that allows the risk to be dealt with on two separate fronts: control of the molecular manufacturing capacity, and control of the products. Such a system has many advantages. A well-controlled manufacturing system can be widely deployed, allowing distributed, cheap, high-volume manufacturing of useful products and even a degree of distributed innovation. The range of possible nanotechnology-built products is almost infinite. Even if allowable products were restricted to a small subset of possible designs, it would still allow an explosion of creativity and functionality.

Preventing a personal nanofactory from building unapproved products can be done using technologies already in use today. It appears that the nanofactory control structure can be made virtually unbreakable. Product approval, by contrast, depends to some extent on human institutions. With a block-based design system, many products can be assessed for degree of danger without the need for human intervention; this reduces subjectivity and delay, and allows people to focus on the few truly risky designs.

In addition to preventing the creation of unrestricted molecular manufacturing devices, further regulation will be necessary to preserve the interests of existing commercial and military institutions. For example, the effects of networked computers on intellectual property rights have created concern in several industries, and the ability to fabricate anything will surely increase the problem. National security will demand limits on the weapons that can be produced.