Cubby doors would definitely be possible, although the problems there would come the hinge and latch. maybe some kind of metal piano hinge you screw on would work (the plastic hinge on one of my doors broke, stupid design to make them plastic). The latch and lock would be the hardest thing to make, and wouldnt be a factory solution. Something like this would work where it just rotates around behind the original latch rod. Now that I think about it I also really like the idea of removing the key and just having a push button like in this second picture, that way you wouldn't have to worry about yet another key that doesn't match the rest of the car. May look into making some doors, let me know your ideas