A easy to print Beach Rocket that you can toss back and forth to each other.

It can be printed using Vase Mode. 

The slots at the top are there to create extra mass and move the center of gravity further to the tip. Also they increase the impact resistance of the rocket.

My test prints where done in PETG using VaseMode, 0 bottom layers  and a 0.6mm nozzle. If you are using a 0.4mm nozzle you might want to increase your extrusion factor.