It's against the law to download a pirated £0.99 MP3. But it seems that printing your own £249.00 iPod is fine

That's one implication of this very useful paper on the state of UK law on 3D printing, by the excellent Simon Bradshaw.

The paper explains that under UK law, you can print an awful lot of things with no legal comeback. 

Some interesting points from the article: Printing a copy of a patented item for private, non-commercial use, does not count as infringing the patent. However, uploading an electronic file of a patent probably is illegal, since it provides others with a means to infringe the patent, which is specifically prohibited. Copyright, eg for artistic originals, largely is protected.

design rights have a similar exemption to patents. This may even be true if these users use a 3D printer in a public "copy shop". There's a further loophole in that it's less clear that providing others with the means to infringe a design right is illegal. So while patents and design rights stop companies from copying each other's products and selling them, they provide much less protection from home users. An interesting catch is that schools and universities, while non-commercial, aren't private, so while pupils may be able to print out their own iPhones at home, doing it at school would be patent-breaking.  

So, tech permitting, and if some reprobate sends you the specs, it looks like you can print your own iPhone**. Be prepared for interesting times in the world of IP. * Of course, most 3D printers now are pretty basic, and print in plastic. Printing a working iPhone is still some considerable way off. But 3D printers can print in more and more materials, at ever greater degrees of resolutions, so chances are these legal points will become relevant quite soon.