Suspect the materials and design are altered relative to a traditional process of manufacture of a part fulfilling the design requirements.
Printing usually cuts time-to-availability in exchange for more expensive materials to achieve a functional goal. Some aerospace applications substantially cut time to manufacture and achieved a 10-15% reduction in weight.
The fuel injection nozzle plate for a rocket engine was created in less than 4 months by printing, versus a year plus quote from traditional manufacturing sources.
http://heroicrelics.org/info/f-1/f-1-injector.html
I do not have the ability but I can see the uses of this such as fixing the annoying door handle on my Honda Accord that has sharp plastic chrome ‘paint’ ($10 at Amazon) or the arm rest with the splintered top that cost me $130 to replace (part cost, I installed it).
The door handle is complex with several parts https://www.youtube.com/watch?v=-OHtTza3Ob0 Amazing it cost less then $10. Only if the part is rare can I see the benefit other then it is cool to do.
Maybe build toy parts like for a drone. They crash or get shot out of the sky all the time.
The comments are interesting.
pittanceSmack-Fu Master, in training
I’m on the second year of a printed replacement drive pulley for my lawnmower (http://www.thingiverse.com/thing:780471)