This is a functional remix of HipsterLogic's toy rocket design. I've added some components as well as made some modifications to the code which will allow you to create model rockets of arbitrary diameters to accommodate engine sizes and other design considerations.

It goes without saying that building and launching a rocket based on this design is something that you are undertaking at your own risk and you should not try to launch anything based on these designs without a functional knowledge model rocketry as well as how to prepare 3D prints for the speeds and forces that the parts will be subjected to during launch.

Please follow all local laws, and consult with the very knowledgeable model rocketry community if you have any questions.