Helen Sloan of World Trademark Review writes an interesting analysis of the effect of 3D printing on trademarks. This was prompted, of course, by the recent announcement by The Pirate Bay that they're adding a category for 3D object files. The implication is that anyone would theoretically be able to download a 3D model of a commercial product and reproduce it at their home without paying the designers and owners of the product.
Sloan's analysis correctly shows that scenario is highly unlikely to happen in the near future for any interesting commercial products. It may indeed happen for commodity-type objects, such as generic construction hardware or very simple replacement parts, but those items are usually not at issue when it comes to trademarks. Even if something is copied, legal steps can be taken that echo what's done today when counterfeit products are discovered.
But, as Sloan says, the problem shows up in homes equipped with a futuristic 3D printing capability: millions of people can individually reproduce objects and it would be extremely difficult to track them all down.
Sounds a lot like the current state of the music and movie industries, doesn't it? Perhaps a solution will emerge before 3D printing capabilities can catch up to matter.