An engine includes at least one pulse detonation chamber configured to receive and detonate a fuel and an oxidizer. For example and without limitation, before determining to perform a particular hand-off, various aspects may comprise storing beam-forming information associated with the particular hand-off. The crown sector element is cast in place between the side elements. The patterned surface is then planarized and selectively etched to expose patterns comprised of one of the types of film to a predetermined depth to produce a selectively etched surface.