3D printing is huge at the moment, with DIY models starting at $400 and ranging up to $2000 for ready built replicators. Nokia has also taken notice of the uptrend in 3D printing and has released 3D design files for the Lumia 820 cover.
Nokia was the first to bring us cell phones with swappable cases back in the 1990's and now they are hoping to refuel the custom case craze that once was. The Lumia 820 already has a range of colored rear covers, but the Finnish company wants you to print your own on a 3D printer.
The design files were released on Nokia's developer site and can be download by anyone who creates a free account on its website. As a long time proponent of 3D printing and a 3D printer owner, I wish more companies would begin doing this. I would even be willing to pay up to a few bucks for a design file of a simple broken part that I could print out at home.