Estes Little Joe II (Small) Build, Part 5, DIY Centering Rings

If you have good, sharp scissors you can cut the outside of the rings with them.
Here I cut right down the pencil line. I want a bit of a border so the rings can be sanded to fit the BT-58 tube.

As usual, I made two extras and will pick the best of the four.

All the rings were slipped over a BT-5. The outside edges were gang sanded. The central tube gives support and alignment while sanding.

The rings were punched for the engine hook.
On the other side is a small hole for a replaceable Kevlar line.

I used a rotary punch to make the notches. Here I'm cutting off the bottom of the round punch for a squared corner.