I started by laser cutting the fins and their centering rings from a sheet of 0.25" plywood. This size provided a good balance between low weight and physical sturdiness.

Next, I epoxied the fins and centering rings together and installed the motor tube and parachute attachment ring.

With the fin can complete, I began working on the airframe.

Before integrating the airframe and fin can, I cut slots in my cardboard airframe with a boxcutter and a carpentry square. This allowed the airframe to fit around the fins, so I inserted the fin can and epoxied the two parts together.

Before integrating the airframe, I tied a length of shock cord to the fin can's parachute ring. After integration, I pulled the cord through the airframe and tied 2 bowline knots in it, one halfway through, and one at its end. These would attach to the parachute and nose cone respectively. 

The rocket motor contains an ejection charge that sits at the bottom of the airframe. When it fires, it pushes out the parachute, allowing it to inflate and slow the rocket for landing.

After a fresh coat of paint, my rocket was ready to fly!

During the first launch attempt, the ejection charge fired but the parachute was snagged in the airframe. Fortunately, my rocket survived the hard landing. Because I designed the fins to be swept back, the sturdy fin can was the first part to hit the ground, and it was able to absorb the landing force.

After smoothing out a snag point on the inside of the airframe, I launched again and the parachute successfully deployed.

By successfully launching and recovering the rocket, I earned my Level 1 High Power Rocketry Certification!