So 3D printing organs is not cut and dry and usually has issues ex-vivo (outside of the body) because of poor vasculature formation (little transfer of nutriens and waste).
The best 3D printed organs right now are made by forming a 3D scaffold that is seeded with appropriate cells (Mesenchymal stem cells for bone, muscle, and tendon). To promote correct cell growth and differentiation, these scaffolds have appropriate physical, chemical, and material properties similar to the adult human organ you are trying to replicate, but better at promoting cell infiltration, differentiation, and replication within reasonable bounds. Sometimes these scaffolds are made up of decellularized cadavaric tissue (ghost organs)
These artificial organs often lack complex structure and stem cells can form teratomas if they differentiate incorrectly. Right now only a few organs can be tissue engineered. These include (bone, skin, bladder, and intestine). Tendons, nerves, and muscles can be encouraged to grow and repair in the body via tisdue engineering but forming complete replications is very limited. Complex organs like livers, kidneys, and adrenals can be "replicated" with organoids to have similar functions but look and work very differently. These organoids are good for treatment testing and for understanding diseases.
The major limitation of tissue engineering right now is that people with genetic disorders or are older cannot have their own cells used to replace their faulty organs unless they are genetically modified. You can theoretically match donor phenotypes, so that allogenic transplantees don't need to be on immunosuppressants. Lots of progress is being made over all but we are far from replacing organs like you would a cars parts
The Computer-Aided Design ("CAD") files and all associated content posted to this website are created, uploaded, managed and owned by third-party users. Each CAD and any associated text, image or data is in no way sponsored by or affiliated with any company, organization or real-world item, product, or good it may purport to portray.