this CO2 powered rocket uses 90mm long 20mm wide CO2 canisters made for "pumping" up bike tyres. to launch the rocket I made a wooden thing with a nail and a lever to puncture the metal foil that's containing the CO2 as well as a guide rail. the rocket ring is to be glued to the main rocket so they can slide along the guide rail. I printed them with 3 perimeters, no top or bottom layers and 0% infill.