In the late 1970s 3D printing started to become established as a manufacturing technology. Thirty years on the cost of 3D printing machines is falling to the point where private individuals in the developed world may easily own them. They allow anyone to print complicated engineering parts entirely automatically from design files that it is straightforward to share over the Internet. However, although the widespread use of 3D printers may well have both economic and environmental advantages over conventional methods of manufacturing and distributing goods, there may be concerns that such use could be constrained by the operation of intellectual property (IP) law. This paper examines existing IP legislation and case law in the contexts of the possible wide take-up of this technology by both small firms and private individuals. It splits this examination into five areas: copyright, design protection, patents, trade marks, and passing off. Reassuringly, and perhaps surprisingly, it is concluded that – within the UK at least - private 3D printer owners making items for personal use and not for gain are exempt from the vast majority of IP constraints, and that commercial users, though more restricted, are less so than might be imagined.