A method of manufacturing a composite interbody device, comprising: assembling superior and inferior endplates, including: forming a porous titanium core interface layer on a core interface side (128, 210) of a solid titanium central barrier layer and forming a bone interface layer on a bone interface side (126, 202) of the central barrier layer, opposite the core interface side; wherein the core interface layer, the central barrier layer and the bone interface layer are formed as a single titanium sheet having two distinct sides, a micro porous side and a side with a plurality of machined surface features, the micro porous side serving as the core interface layer, the solid middle serving as the central barrier layer and the featured side forming the bone interface layer; placing the inferior and superior endplates in a mold, on each side of a core cavity, with the core interface layers facing the core cavity and the bone interface sides facing away from the cavity; and injection-molding molten plastic into the core cavity, to form a plastic core (104, 304) between the endplates and bonded with core interface sides of the core interface layers; wherein molten plastic extrudes into pores (129, 214) of the core interface layers, to bond with the endplates, and wherein the central barrier layer of the superior endplate and the inferior endplate prevents the molten plastic from over-extruding into pores (127, 208) of the bone interface layer, reserving the bone interface pores for bone in-growth. assembling superior and inferior endplates, including: forming a porous titanium core interface layer on a core interface side (128, 210) of a solid titanium central barrier layer and forming a bone interface layer on a bone interface side (126, 202) of the central barrier layer, opposite the core interface side; forming a porous titanium core interface layer on a core interface side (128, 210) of a solid titanium central barrier layer and forming a bone interface layer on a bone interface side (126, 202) of the central barrier layer, opposite the core interface side; wherein the core interface layer, the central barrier layer and the bone interface layer are formed as a single titanium sheet having two distinct sides, a micro porous side and a side with a plurality of machined surface features, the micro porous side serving as the core interface layer, the solid middle serving as the central barrier layer and the featured side forming the bone interface layer; placing the inferior and superior endplates in a mold, on each side of a core cavity, with the core interface layers facing the core cavity and the bone interface sides facing away from the cavity; and injection-molding molten plastic into the core cavity, to form a plastic core (104, 304) between the endplates and bonded with core interface sides of the core interface layers; wherein molten plastic extrudes into pores (129, 214) of the core interface layers, to bond with the endplates, and wherein the central barrier layer of the superior endplate and the inferior endplate prevents the molten plastic from over-extruding into pores (127, 208) of the bone interface layer, reserving the bone interface pores for bone in-growth.