Would 3D printing technology allow you to create a replacement ignition or door key? I don't ask because I need one nor do we lack places to get them done with either the code or a good photo, it's more a question of could it be done by someone you don't want to have your key?
The newer cars out there with microchips in them seem to be safe, but if you could get a close enough photo to make your printed key accurate enough to be useable, it could open up a can of worms at some point. Cameras are getting really good at resolutions and it's not that far fetched to think of a tow truck driver or shop mechanic quickly getting an image of your key, making note of where you live, and then having his buddy come get your car when you're not home. Maybe a little "conspiracy theory" to some extent, but we seem to see many great new technologies get quickly used for the powers of evil and not good.