Most attempts at creating artificial veins don't come close to replicating organic processes, but researchers at the Queen Mary University of London might change that. They've developed a technique that makes proteins and peptides self-assemble into tubular shapes that could stand in as arteries, veins and similar structures. There's no 3D printing or moulds involved -- you only need to guide the material as it builds itself. It can even grow and heal, so you're not stuck if it needs improvements.
As you've likely gathered, the discovery could lead to vein implants that behave more like the real deal. That's not just useful when you've suffered an injury, though. Scientists could also use these veins to study diseases like Alzheimer's in conditions that are much closer to reality, which might produce better treatments. In short, these self-assembling tubes could improve your health across the board -- not bad for a little piece of synthetic goo.