The holy grail of a self replicating 3D printer is the ability to print its own drive train. In the long term this may be possible with some form of multi-metal stintering system that can produce a stator layer by layer. However in the near term a more viable DIY option may be to use a piezoelectric “PCB Motor”.
The printing, routing or embedding of wires to form a circuit board track is now common place and with pick and place of components well on its well this could become feasible sooner than thought.
There was already an an entry on the RepRap wiki regarding PCB motors but I cant find any evidence that they have been successfully used.
Capolight Electronics Projects. 
It would probably be easier to make a useful linear version of this, which could be very advantageous, though it would require a significant redesign of the bot. With some chemical post-processing, we might be able to grow our own piezo motors using 3d printing and a process similar to this: http://hackaday.com/2011/03/15/cooking-up-piezo-crystals-at-home/
“…and the patented principles behind the technology…”
I haven’t looked into the particular patents, so I haven’t the slightest idea of their validity, or whether they could be bought outright by a suitable non-profit, but I imagine this could otherwise be a major obstacle for the RepRap project adopting these.
See me username = Esurname on youtube
For Robotics and Flat brushless p.c.b motor experiment..you may find it useful.. for RepRap projects. I’m saving for a RepRap 3d printer..now..
NOTE 🙂 not all my videos are on my website
How about MTBF? I know tha life time of pieso motors less 10’000