my brother worked for mother theresa's hospice in india, 25 years ago. it wasn't what you'd think. they had a number of people come in from different outside organisations who tried to order people around: this being india they of course didn't listen, because why should they listen to foreigners?
so my brother stayed there and worked with them for six months before advising them to build a brick out-house for effluent, to change the sheets on the beds when somebody died, and to wash the needles in between injecting one patient and the next.
it also didn't help that as mother theresa got older, she began to lose her memory and would wander off, go to sleep, taking the key to the medicine cupboard with her so that nobody could get access to it for an entire day.
ghandi on the other hand is a far better choice for discussion, here. i love the story where he was asked by a mother to tell her son to stop eating sweets: he told her to come back in 2 weeks. when they came back, he said, "stop eating sweets!" and the son went "yes yes mr ghandi!!". the mother, perplexed, asked "why didn't you do that 2 weeks ago??" and he said "because i had to first give up sweets myself".
now *that's* inspiring, and it tells you something that we can learn from this fuss over 3D printing. there's no point asking "what would ghandi do with a 3D printer" because it's the principles that ghandi applied in his life *whenever he met someone* that are the key. it's never about the technology: it's about the people and what they face.
the point is: asking this question is silly. what you need is just to have the 3D printer, and go wander around the world, meeting people. you'll soon find problems that can be solved with it.