An apparatus includes a glass body having a first face and a second face on opposing ends and defining a longitudinal axis between the opposing ends. The glass body includes multiple planar exterior surfaces, each extending continuously from the first face to the second face. The glass body also includes an interior surface surrounding an aperture, the aperture extending longitudinally from the first face to the second face. The glass body further includes a plurality of holes surrounding the aperture, where the holes are disposed within the glass body and extend longitudinally from the first face to the second face. The holes are configured to receive and direct a gas through the holes to exchange heat between the gas and the glass body.