There you can download the files for sc1 and kw1 keys, the two most common in the USA.
To generate new keys, you can just edit the last line of the file and enter in the key code for your key. If the code isn’t written on the key, you can measure the height of each bit and compare to the numbers in the Root Depth column on the aforementioned pin depth site. Perhaps more nefariously, you could implement something like SNEAKEY to generate key codes without physically measuring the key.
So this is where we cue the fear or the favor.
Do we celebrate that this gives us the potential to print out a spare key to keep under the doormat by the front door or to churn out a temporary key for your neighbor so they can feed your cat and water your ficus while you are on holidays?
Or do we worry about creepy guys at nightclubs taking photos of your keys with their cell phones so they can race home, print out a key, come back to the nightclub and get your address off of your drivers license (because they forgot before) then go to your house, let himself in with his 3D printed key and take weird photos of himself with your toothbrush or some other urban legend? Or they could use Ditto Key anyway..
Watched the 'gestural/Kinect//3D print/reprap video and the realtime print out of the gestures was fastinating as a process. As with these new ways of interacting and the first go with them, outcomes can be incredibly ugly. At least the video did start me thinking. Using Kinect and not being grounded, your propriosense has to be pretty acute like Swedish design firm FRONT have (http://fabbaloo.com/blog/2008/11/20/sketch-furniture-into-reality.html). Maybe 'snap' in some form (a 'dog with 3D printed sabre-tooth tiger fangs' perhaps) should be added to gesture capture software and, as 3D printing is a 2D layering process, a transparent non reflective surface used to draw on. If it is the outcome that is more important best use a 3D forcefeedback sketch/modelling package like Cloud9 which supports movement, enables you to feel where you are in 3D space and is not prescriptive like CAD. And lots of fun to use.