I posted a video of this on FaceBook, and my friend commented as per the subject. Not that key cutting is criminal, but I get what he is saying. It's the challenge!
Yes, you can simply print a typical key on a 3D printer in 10 minutes and it does actually work a work!
To my surprise it does not even wear out that quickly - we have been playing around with this key quite a bit. Obviously nothing like as durable as a metal key.
I decided to design it from scratch as that is more fun, and it took me around 5 attempts to get it right. One of the key things was which way to print the key. As the print is built up in layers this matters. Printing it "up right", i.e. the bit you hold at the bottom, created a key that simply snapped when turned as that puts force between the printed layers. Printing horizontally worked a lot better.
I may have a go as higher security keys later. Just for fun.