We're building a typical fiberglass model rocket kit here from a company called "Mach 1." The kit does not come with very detailed instructions, and some of the parts need post-processing to get them to fit together. So we decided to make a series of videos to help you out if you're building something similar. This part of the build shows how to attach the shock cord to the engine mount tube. Then the temporary kevlar cord is woven through the holes on the aft centering ring so that the ring can be easily removed from the tube of the rocket after the fins have been tack-glued to the engine tube. You'll also see how to insert the Apogee style rail button into the body tube from the inside wall of the rocket.