This rocket only takes one way trips. Load in up to eight firecrackers that ignite using the exhaust from the model rocket engine, and hopefully explode at the peak of the rocket's flight. The holes in the body are meant to be whistles similar to the whistles on a Nerf Vortex football. I don't know how well they work yet because I have yet to launch my rocket. The rocket requires standard A, B, or C engines, and firecrackers that are 1/4" in diameter. Print the rocket using a low infill and preferably 1 perimeter to limit the weight. Insert the firecrackers first, then slide in the model rocket engine. If any of the firecrackers are loose, make sure you glue them in place to keep them from being left on the launch pad after takeoff.