I'm a firm believer in Surgeon's End Loops. When building my rockets, I attach kevlar leaders to the motor mounts and put a surgeons loop on the end of it, to attach elastic shock cords, nose cones, chutes, streamers, beepers, whatever I need.
A buddy has a wife who's into sewing, and has a heavy-duty sewing machine, and he stitches the loops into his tubular nylon cords. He lays it flat, folds it over to make the loop, and stitches down a 1.5" section using a very heavy thread. Since knots weaken a line/rope/cord, this prevents that weakening.
WW