Now a 3d printer is a very simple device. It produces some awesome results. but consider this. A normal 3d printer prints slices or layers of a desired object in pass after pass in one of two ways, either spraying a resin / agent into a dust bed in a particular pattern hardening the mix in a very specific way, or by laying down tiny layers of self adhesive agent.
Either way the desired construct is built the same way with minor changes. What say you to using live cells in place of cornstarch, or polymer? Well scientists at Wake Forrest are thinking the same thing and are working towards being able to actually “print” a kidney. If this development goes through as planned image a world with off the rack replacements, without the need of a human doner? You could theoretically have a copy of your own organ printed…