I have been hesitant on creating this blog post because on one hand, I want to divulge everything I did to see if this was really a viable threat to society so that you can be fully informed, but on the other hand, I don't want to educate people who don't know how to do this - how to do this. I decided to keep it dumbed down on purpose and leave out some significant steps.
That said BEWARE! If someone takes a picture of your keys and gets a clean profile of the target key, a 3D printed key can be used to open that door! So think twice about just leaving your keys sitting around out in the open. What a world.
I mean, you shouldn't even leave them out now that people are going around scanning randomly to steal cars with your FOB's radio output - so if you don't know about that, BEWARE! don't leave your keys out - especially hanging by the front door.
At the time of doing this test, I was living at an apartment complex where we had one key for our apartment deadbolt, the deadbolt to our garage, the doorknob to the garage and the small storage shed's doorknob on the patio. I took a picture of the key. Of course, since I only wanted to try this once, I did take the key off and lay it flat for the picture. In this process I learned that there isn't a lot of tolerance to exacting key specifications in the actual lock itself so even if you're off by a little bit - it'll still work. Just need to get the tumblers to line up close enough to allow the cylinder to turn. Also in this process I learned of some other products out there you can get like a "bump key" or even a whole pick set that comes with locks for practice. I learned a lot about some of the simple things we rely on to keep us safe may not keep us as safe as we think. Of course, this key is years old and the complex changes locks so it's still completely random for me to post this picture of a key.
That being said, if you don't fortify your door, someone can just kick it in without a key in the first place. In the interest of safety, you may want to consider doing that. I found there are a number of products that will take one small step towards better security when fortifying a door from being kicked in. Usually just takes a larger strike plate (where the deadbolt slides into the door jamb) and longer screws (there should be multiple framing pieces around doors you can screw into making it stronger. I have one similar to this in the banner that has all the plates and screws needed:
Any one will do and these can be found anywhere - but they won't help if someone has a key. Here's where I'll be vague for safety sake. I was able to create a 3d object from the picture that represented the shape of the business part of the key. I was able to reverse it and apply it to a blank key that was unfortunately very easy to find and basically digitally cut a key from the blank.
I printed this in PETG which was strong enough to open all of the door knob locks without any effort at all. The deadbolts on the other hand took a little finesse to not break the plastic key. I could have still made the key a little thicker or use something more rigid and strong like ABS plastic and I would be able to use it as my normal key. Great for making copies or hiding a key somewhere - bad if someone wants to get in your house and snaps a pic of your key.
Anyway, pretty soon we probably won't even be using keys and we'll just use electronics, retina scans, thumb prints, whatever.