This is a 3 piece model rocket I designed to take Estes E-class engines. There is a 'launch lug' on the outside of the fin section to fit over a 3mm guide rod which I recommend to keep the trajectory straight during launch.

There is also a similarly sized internal lug in the mid section tube for attaching the parachute cord and nose cone. For the parachute cord I use 3mm para-cord as it needs to be quite strong to take the force of the ejection charge.

The parachute itself is made from rip-stop nylon sheet, which I cut into a hexagon shape that is 600mm across the flats. Light weight kite string is tied to each corner of the parachute and each length is approximately 500mm long, the 6 strings come together and are each tied to the para-cord.

The fin section and mid section are glued together using 2 part epoxy and the nose cone is designed to be held in place with a secure friction fit.

Additionally, I have made the motor cover plate out of 1.5mm aluminum sheet which I cut out by hand, but you could easily3d Print or laser cut one that would do the job ok. The purpose of the plate is just to stop the rocket engine blowing itself out the bottom when the ejection charge goes off. 4 M3 x 10 cap screws are needed to hold the plate in place.