Shepherd's whistle
They are also produced commercially. Simple whistles may cost less than 1 USD in bulk; expensive ones may be quite ornate. They are commonly made of plastic, aluminum, stainless steel, silver, brass, titanium, Corian, jade, buffalo horn and other materials.
Moon Whistle
"Moon Whistle" is a story-based role-playing game, featuring sprite characters and objects, 2D exploring maps, cutscene dialogues, and combats ― conventional fares of old-school role-playing games as a whole. The game's prominent feature is its setting; contrary to a regular save-the-world plot in a high fantasy setting, the story of "Moon Whistle" unfolds mostly in a fictionalized modern Japanese city completed with original chip sets and character sprites. Much like the "Mother" series, most of main characters are preteen children. Their wielding weapons are everyday items and toys, they wear casual clothing or mascot costumes instead of a piece of armor, and monsters they fight include weird ones like burner/tripod monsters and iron frogs. The entire music was composed for the game by the pseudonym Saia Hyōseki (氷石彩亜).