With something that needs to be rugged for day-to-day usage, you do not want to 3D print something like a key.
I've experimented printing a bracket with 100% ABS infill and it's still not very strong. The plastic filaments are very weak and when printed, are layered (versus vacuum formed).

 

hi all, i just wanted to chime in here with an unsolicited plug for Bruce (valvashon / Mini Key Hospital), as everyone is figuring out, these keys have electronics in them so it's not as easy as just getting a key cut. If you've lost your key you don't have many options because of the little chip inside that talks to the car.

But if you have a key thats tired/damaged then Bruce can rebuild your key for a very reasonable price. For me he rebuilt the key into a flip key (like on VWs) and it is 100% functional--even with him cutting a new key blade.

I looked at the options to DIY (and did a half *** job my first time), and it is doable to move the guts of a damaged key into a new shell if that's all you need as well.

And to point out the obvious there are 2 key options from the dealer, the one with the remote and a manual key that does not have remote unlock but will start the car. The w/o remote is cheaper, but the feedback from Bruce (who has the most exp with keys here!) is that the door locks aren't designed for constant use so there is risk that you'd wear them out using the manual locks on a regular basis.