zip gun

noun2

1. •
   A crude homemade weapon that fires a projectile.

   • As pertaining to my idea of zip guns, we didn't use the old type of zip gun any more because they were too dangerous. That was just a pipe and a piece of wood and nail and rubber band. — 1968
2. •
   An EVA astronaut space maneuvering propulsion unit, a handheld gas jet device, connected to a reservoir.