Well, perhaps not the "replaceable parts", but that is doable with a 3D printer. I doubt Brother would come after you for printing a new output tray hinge or custom-colour button set ... and I doubt any other parts are likely to outright 'break' (my laser printers of various brands have lasted around two decades each). Any other parts, such as the image drum, would require too specialized fabrication to be done at home or at the local fab lab.