Here is a fun kit that lets you build a metal water rocket launcher. The StratoLauncher IV Water Rocket Launcher has aluminum, plastic, and brass parts.
The Stratolauncher's carrier aircraft, like its real-world inspiration, is powered by six J-33 "Wheesley" Basic Jet Engines. Control is provided by a Stayputnik Mk. 1, with SAS capability provided by a CH-J3 Fly-By-Wire Avionics Hub. ...