High Quality Content by WIKIPEDIA articles! The panerusan instruments or elaborating instruments are one of the divisions of instruments used in the gamelan. Instsead of the rhythmic structure provided by the colotomic instruments, and the core melody of the balungan instruments, the panerusan instruments play variations on the balungan. They are usually the most difficult instruments to learn in the gamelan, but provide the most opportunity for improvisation and creativity in the performer.