Estes DARC-1, #7307 Build, Part 26, Ends & Edges

The inside engine retainer ring (Part H) is glued onto the end of the motor tube using medium CA glue.

Here's how the ends of the two shock cords are tied in a loop.

Both are jointed to the parachute shroud lines. I used a separate length of #10 embroidery thread to tie them together.

This could be a problem - 

With both of the shock cords at the same length, the two body segments would bump into each other after ejection.

I'd recommend two different shock cord lengths so these could hang one above the other.

Here you can see how the parachute is held in the compartment. The top fin prevents the chute from falling out the back end during boost.