A flexographic printing sleeve or plate is made by a method that includes providing a millable polyurethane, crosslinking the millable polyurethane, and forming a relief by at least laser engraving the crosslinked millable polyurethane. For example, crosslinking may be accomplished by a peroxide-based process or by a vulcanization process using sulfur. A relief in one example is formed by extruding the millable polyurethane, thermally crosslinking the polyurethane after the extrusion step and laser engraving the crosslinked millable polyurethane. A printing article is formed into the shape of a flat printing plate or a continuous in-the-round printing sleeve.