There are machines that can 3D print a stainless steel helicopter rotor. Culinary specialists use a basic machine to spurt batter and frosting to make magnificently shaped cakes. Researchers are using huge 3D printers to extrude concrete to form buildings. Another type can layer cultured human cells to literally print a kidney. Check that out here. Even the Objet260 connex (their desktop version) can create a multi-material part with 14 possible materials in a single build.
This is made possible by the microprocessors embedded in the 3D printer. After reading the file, they give commands where to put material and what movements the printer head should make to build that specific object. Because of this build process, the machines are becoming less and less limited by materials. This means that whatever solid objects a human can conceive, they can be created using a single machine. For a more traditional manufacturing technique like injection molding the ability to make an object is carried out through mechanics and hardware so that only one object can be made by the hundreds of thousands.
Another major benefit of 3D printing technology is sustainability. It extrudes the exact amount of material needed, with no excess (one exception is printing support legs for an object with significant overhang). An image that comes to mind is when opening a checkers board game, the circular pieces are still connected to the plastic web that holds them in place during manufacturing. In machining metal parts with subtractive manufacturing, material is cut away to produce the final product. 3D printing is a type of additive manufacturing. Imagine all the waste and inefficiency you don’t see!
The technologies behind the printers are innovations, but more importantly they create pathways to further innovation. How will products we now use be redesigned and reconstructed using these techniques? As more people are exposed, the scope of homemade design will proliferate allowing products to be more available for cheaper.