This creation almost defies belief - a fully functional 3D printer, inside Minecraft. How does it work, you ask? That's a really good question - and not one I ever found an answer to - but there is a lively discussion going on about that very subject.
ItsJustJumby created this monster, and says that it can print in all 16 wool colors in a 6x9x10 area, with any design you can imagine (within those dimensions). Win.