I expect it to be similar to what happened with the printing press and computers in that you'll be able to download (/pirate) actual objects. The revolution will be huge.
The best machine gun in Mass Effect 2 has "Fabrication Rights Management" technology which prevents you from printing one for each member of your team. I doubt real-world engineers for companies whose products would be most affected by downloadability are too far behind.
I'm excited to see what happens as the patents in this space expire. I'm expecting it to be similar to what happened with steam engines.