A system and method for securely streaming encrypted digital media content out of a digital container to a user’s media player. The process of preparing these ethylenically unsaturated macromers comprises reacting a monofunctional compound which corresponds to a specific formula with at least one alkylene oxide, in the presence of at least one alkoxylation catalyst. Then, the substrate is etched to a predetermined depth while using the second mask as an etch mask, thereby forming the protruding portion.