Model Rocket Fins and Nose cone

I had a bunch of these strong little cardboard tubes lying around (25mm outer diameter, 1mm thick) so I decided to make some rockets out of them.
I think standard A or B engines will work with this (need spacers though)
This piece is made to slip snugly over the cardboard tube, then glue in place.
There's a nose cone on the way that will fit inside the same tube. I'll try to add it to this thing so they're together.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/e1sJ17UHeHQ
https://www.tinkercad.com/things/0mapQktegQp