3D printing from abundant sources: fusing sand into glass, powered by the sun
You should see this amazing solar powered 3D printer that sinters ordinary sand into glass. Both the source of energy and material are pretty much unlimited. I wonder if you could one day print entire sand castles, that you could actually live in! Of course we need to be able to 3D print those fresnel lenses out of sand… Plus we need to move the lens, not the castle (unless you’re Mohammed). Perhaps that can be achieved in the way I proposed here.