This is a work in progress. The few launches that I tried, all failed. The rocket comes out of the tube and tumbles end over end. Please let me know of tolerance issues. I will update as I can. I'm still pretty new to Fusion360.

!!!BE SAFE - CO2 CONTAINER IS UNDER HIGH PRESSURE CAN BE VERY DANGEROUS!!!
!!!ATTEMPT TO BUILD AT YOUR OWN RISK!!!
!!!THERE IS AN EXPLOSION AND SHRAPNEL RISK!!!
!!!THIS IS NOT A TOY!!!
!!!NOT ADVISABLE FOR CHILDREN!!!
!!!DO NOT USE IN CROWDED AREA!!!
This is a Remix of https://www.thingiverse.com/thing:1663930.

You will need...
1.25in PVC pipe
1.25in PVC pipe cap
PVC Glue
0.75in Wood Screw

Assembly...
Glue cap to the end of the pipe. Find the center of the cap. Screw the wood screw up through the cap.
Insert 12oz CO2 cartridge in the open end of the plastic rocket with the skinny part of the cartridge towards the bottom.

How to use...
Place pipe with the cap and screw side down on the ground in an open field. Point open end towards the sky. ALWAYS KEEP THE PIPE POINTED IN A SAFE DIRECTION!! MAKE SURE THAT NOTHING IS OBSTRUCTING THE PIPE. KEEP YOUR HANDS AND FACE AWAY FROM THE OPEN END OF THE PIPE!! DO NOT POINT AT PEOPLE OR OBJECTS YOU DO NOT WANT TO HIT!! Drop CO2 Rocket down the tube. The screw at the bottom will puncture the cartridge and release the compressed gas. The rocket will come out of the tube at great speeds! The fins should deploy on their own once rocket has left the tube. Keep watch on the rocket as it travels through the sky. Retrieve rocket when it has come back down.

!!!BE SAFE - CO2 CONTAINER IS UNDER HIGH PRESSURE CAN BE VERY DANGEROUS!!!
!!!ATTEMPT TO BUILD AT YOUR OWN RISK!!!
!!!THERE IS AN EXPLOSION AND SHRAPNEL RISK!!!
!!!THIS IS NOT A TOY!!!
!!!NOT ADVISABLE FOR CHILDREN!!!
!!!DO NOT USE IN CROWDED AREA!!!