3D bioprinting uses a layer-by-layer printing process to construct living human tissues and organs by depositing hydrogels, collagen, and cells. Over 6,000 people in the UK are waiting for organ transplants. The technology has the potential to print organs like livers, kidneys, and even hearts to help address the shortage of donor organs. However, 3D bioprinting also raises ethical issues and implanted organs may face rejection by the human body.