A means of completely rebuilding a still living human body without the need of major surgery or looking like Frankenstein's Monster.
As in, you've lost an arm or a leg, we'll build you a new one just as it used to be. Lost an eye or your hearing, we can go in a fix/replace them at the same quality or better. Need a new liver, kidney, heart, etc? Take a dozen if it suits you. Or maybe you've always wanted wings, gills, or a tail. Sure thing mate. Don't like your height, your build, the color of your eyes/skin, your gender, the shape of your head, or any particular mental condition/physical aliment? You can change them. Want to stay in your teens or twenties? Then yes you can.
Basically, I'm looking for something like Wolverine's healing factor, but with the ability to also modify your body if there's something you don't like about it.