Take the printed motor cage and ensure a snug fit with the 24" tube. If it's loose add some tape to the tab, if tight sand it down some.
Once you've got the fit up to par, tape or glue the cage in place. I chose aluminum tape. It looks cool and can smooth over issues.
Now it's time to test fit the fins. If all is well glue them into place using CA. Ensure they're all facing the same direction; they have an asymmetrical airfoil to initiate a spin. This is for stability.
Install the bottom of the nose cone next. Sand or add tape to adjust the fit and glue in place with 1" extending from the 7.5" tube.
Finally install the nose cone. You can apply packing tape to the tube before taping the cone on to allow for a cargo bay. If not, gluing it is acceptable.
Finally, install chute and shock chord. I'm doing this using the normal mounting techniques. I'm working on printing parts for this assembly and a chute cutting guide currently, but for now scour the internet for guidance.