How does 3D printing work, and what can it make?

The answer

3D printing (additive manufacturing) builds objects layer by layer from digital designs, typically using materials like plastic filament, metal powder, resin, or even living cells. The most common method, FDM, heats and extrudes thermoplastic through a nozzle that traces each cross-sectional layer. Modern 3D printers have produced functioning jet engine parts, custom prosthetic limbs, affordable housing (printed in under 24 hours), and bioprinted tissue scaffolds for organ transplant research. The technology has evolved from a prototyping novelty into a manufacturing revolution.