Aspects of the disclosure are directed to treating a substrate, the substrate including at least one of a refractory metal or a ceramic material, and depositing a media onto the treated substrate to generate a casting core. Embodiments include a fixture, a substrate located on the fixture, the substrate including at least one of a refractory metal or a ceramic material, and a delivery head that deposits media onto the substrate to generate a casting core. Aspects are directed to a core configured for casting a component, the core comprising: a substrate that includes at least one of a refractory metal or a ceramic material, and media deposited on the substrate, the media having a dimension within a range of between 0.5 and 500 micrometers.