Let’s face it. The human body is an imperfect machine working in an imperfect world. For example, damaged heart tissue cannot repair itself. So anyone with a serious enough heart issue must wait for a transplant. Over 4,000 Americans are on the waiting list today. Adam Feinberg, Professor at Carnegie Mellon and his colleagues are paving the way for a new breakthrough treatment using MakerBot’s 3D printers: custom-made tissues and organs for your body. As their findings in the Journal of Science Advances demonstrate, Feinberg and his colleagues have cleared the first hurdle to this treatment. Before you can grow living cells into a tissue or organ, you first need a scaffold in the shape of an artery, organ, or tissue onto which to grow living cells. The problem is, collagen, alginate, and other proteins that might work won’t hold their shape if you just 3D print them. With some inventive modifications to MakerBot’s 3D printers, Feinberg and his colleagues have learned to 3D print these soft gel-like materials inside a jello-like “support bath”. One gel is 3D printed inside another, which is sitting in a petri-dish. After, the support bath can be melted away at room temperature, leaving an intact replica. Feinberg and colleagues have already 3D bioprinted models of arteries and embryonic hearts in this way. Feinberg first started his research with the original MakerBot Replicator®. Since the wood paneling on it couldn’t be easily sterilized, he now mostly uses two MakerBot Replicator 2 printers, even though his lab also has a MakerBot Replicator 2X. Because these printers must be sterilized, they’re placed in a special sealed chamber to ensure that mold and germs are removed. The side panels are removed from the Replicator 2 printers to allow for better airflow, as part of the sterilization process in the chamber. MakerBot’s extruders can’t inject one material inside another. Ever inventive, Feinberg built his own extruder using the original motor from the extruder in the MakerBot Replicator 2. His extruder features a teflon-coated syringe for injecting the bio-materials inside the support bath. The rest of the parts for his extruder were 3D printed on the MakerBot Replicator 2. To operate his extruder, Feinberg paired the open source software from the original Replicator with Skeinforge for a high level of control in his 3D printing process. He could fine-tune parameters, optimize the 3D printing process, and maximize the quality of 3D prints. Beyond publishing the results, Feinberg and his colleagues are releasing their designs under open source licensing. Those STL files and how to instructions will be posted at the National Institutes of Health website. While bioprinting as a field is growing, bioprinters can cost over $100,000 and require specialized expertise, so these innovations might also lower the barrier to entry for other researchers. The next step for Feinberg and his colleagues is to 3D bioprint real heart cells into a 3D printed scaffolding to eventually form a heart muscle.