Fins are on. So’s the body tube coupler. So are the centering rings, and the motor retainer. The motor tube end took a beating with the rings being put on and off. (They were pretty snug, not much of a problem if gluing all three on before installing the motor mount, but the way I did it, putting two rings on after gluing the fins, they really needed a little sanding to loosen them up.) I put CA on the inside of the tube and sanded until it was wide enough for a 29 mm motor.