With the additive manufacturing (AM) or 3D printing process, there's almost nothing that can't be printed from human ears to end-use aircraft components thanks to an ever increasing range of materials, both polymers and metals. So what's been holding back the 3D printing of molds cores and cavities?
Primarily, cores and cavities for the injection molding process need to hold up under the heats and pressures of that environment. Additionally, the surface finish of 3D printed cores and cavities typically is not suitable for the parts and requires some finishing work. So, for years prototype parts have been built using the various 3D processes to evaluate the geometry, look and feel prior to a one- or two-cavity pilot mold being built in which to run actual pre-production parts.