A shaped article can include a substrate formed from a glass material, a glass ceramic material, or a combination thereof and a cavity formed in the substrate. A sidewall of the cavity can have a random textured surface with a surface roughness of less than or equal to 300 nm. A method of machining a protrusion in a graphite block can include translating a cutting tool in a first longitudinal direction toward the graphite block to engage the graphite block with the cutting tool while rotating the cutting tool about a rotational axis without translating the cutting tool in a lateral direction, then translating the cutting tool in a second longitudinal direction away from the graphite block without translating the cutting tool in the lateral direction to disengage the cutting tool from the graphite block. A shaped article can be formed by pressing a preform with a monolithic graphite mold.